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TEXTBOOK 

OF 

MILITARY  AERONAUTICS 


i 


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by    Allied   Air   Kleet*. 


TEXTBOOK 

OF 

MILITARY  AERONAUTICS 


BY 

HENRY  WOODHOUSE 

Author  of  "Textbook  of  Naval  Aeronautics" 
member  of  the  board  of  governors  of  aero  club  of  america,  vice-president 
aerial  league  of  america,   member  of  national  aibeal  coast  patrol  com- 
mission,  chairman   of   committee  of    flying    equipment    cooperating 
with  commandant  of  third  naval  district   in   organizing   naval 
reserve   forces,    trustke  and   chairman    of    committee  on 
aeronautics   national   institute   of   efficiency,    mem- 
ber of  the  society   of   automotive    engineers, 
educational    and    industrial    delegate, 
pan-american  federation,  etc.,  etc. 


NEW  YORK 
THE  CENTURY  CO. 

1918 


Copyright,    1918,  by 
The  Cehtury  Co. 

Publuhsd,  May,  1918 


i 


PREFACE 


One  of  the  purposes  of  this  book  is  to  make 
avaihible  to  our  prospective  American  aviators 
the  educational  information  regarding  the  man- 
ner in  which  aviators  fight  the  enemy — informa- 
tion which  the  enemy  gets  whenever  Alhed  avi- 
ators are  brought  down  and  printed  instructions 
are  found  on  them,  and  by  daily  observations  of 
what  the  Allied  aviators  do. 

The  author  has  found  by  talking  to  Allied 
officers  and  from  the  score  or  so  of  periodicals  of 
the  European  countries  engaged  in  this  war  that 
all  information  about  modus  operandi  and  aero- 
planes and  devices  becomes  known  to  the  enemy 
almost  immediately,  through  the  capture  of 
aeroplanes  and  aviators  and  through  observa- 
tion of  repetition  of  actions. 

Another  purpose  of  this  book  is  to  supply  to 
military  authorities  an  illustrated  pen  picture  of 
the  history  of  the  evolution  of  military  aeronau- 
tics, its  present  status,  and  the  direction  of  its 
development. 

The  hundreds  of  letters  received  from  naval 
officers  regarding  the  value  to  them  of  the 
"Textbook  of  Naval  Aeronautics"  convinced 
the  author  of  the  need  for  a  similar  book  about 
military  aeronautics  rather  than  for  a  book  deal- 
ing with  the  mechanics  of  military  aircraft  and 
their  equipment,  an  extensive  subject  that 
would  fill  a  book  as  large  as  this  volume. 

The  following  excerpts  of  letters  from  the 
commanding  officers  of  war-ships  give  the  gen- 
eral sentiment  expressed  in  the  letters  received 
about  the  "Textbook  of  Naval  Aeronautics," 
which  are  close  to  one  thousand  in  number. 

Acknowledging  the  receipt  of  two  copies  of 
the  text-book,  one  for  himself  and  one  for  the 
ship's  library,  for  the  use  of  the  crew,  the  com- 
manding officer  of  a  United  States  war-ship 
writes : 

I  know  they  will  be  of  inestimable  value.  I  have 
already  spent,  some  pleasant  and  instructive  hours  in 
reading  a  copy  and  must  admit  I  knew  little  of  the 
state  of  the  art  as  applied  to  naval  aeronautics  until 


this  time,  and  I  am  sure  officers  and  men  will  be  aston- 
ished to  know  how  far  this  science  has  progressed  in 
our  service,  and  I  am  further  satisfied  it  will  awaken 
keener  interest  in  this  branch  of  naval  activity  and 
produce  recruits  for  this  service  among  our  skilled 
mechanicians  and  those  daring  souls  to  whom  the  rou- 
tine life  aboard  battle-ships  may  become  irksome. 

There  is  as  much  difference  between  aerial 
warfare  in  connection  with  army  operations  and 
aerial  warfare  in  connection  with  naval  opera- 
tions as  there  is  between  the  operations  of  the 
army  and  navy  proper.  The  naval  aviator  who 
has  to  hunt  submarines,  convoy  troop-ships,  lo- 
cate submarine  mines,  patrol  the  sea-lanes,  and 
manoeuver  his  aircraft  over  the  sea  in  scouting 
or  bomb-dropping  expeditions  must  have  a 
training  which  is  entirely  different  from  that  of 
the  military  aviator,  who  locates  and  watches 
the  movements  of  the  enemy's  artillery  and  in- 
fantry, photographs  the  enemy's  positions,  and 
cooperates  in  attacking  soldiers  in  the  trenches 
or  on  the  march,  etc. 

Hence  the  necessity  of  the  two  books. 

Supremacy  in  the  air  is  the  key  to  victory. 

"Had  the  Allies  one  thousand  more  aero- 
planes, we  could  have  easily  defeated  the  Ger- 
mans." 

This  is  the  general  expression  that  one  hears 
as  the  German  offensive  is  raging.  -  It  is  an  of- 
ficial as  well  as  a  public  expression,  and  every- 
body scans  the  reports  to  find  out  what  the  aero- 
planes are  doing  and  whether  the  Allies  have 
sufficient  aeroplanes  to  maintain  that  supremacy 
in  the  air  which  is  necessary  to  decide  the  war  in 
favor  of  the  Allies. 

With  one  thousand  additional  warplanes,  the 
Allies  would  have  been  able  to  prevent  German 
aviators  from  mapping  the  Allied  positions;  and 
could  have  destroyed  the  militarj-  bases,  muni- 
tion-dumps, gun  emplacements,  the  railroads 
upon  which  the  troops,  munitions,  and  supplies 
were  transported.  In  short,  they  could  have 
prevented  the  massing  of  such  a  huge  body  of 


382116 


PREFACE 


troops  as  the  Germans  massed  for  this  drive. 

Aeroplanes  are  the  only  things  that  can  pass 
the  German  lines.  Thev  can  flv  over  the  Ger- 
man  lines  and  they  can  do  so  at  night,  when 
neither  the  anti-aircraft  batteries  nor  the  Ger- 
man aeroplanes  can  see  them. 

Unfortunately,  the  Allies  did  not  have  this 
additional  aerial  force.  To  keep  one  thousand 
well-trained  aviators  on  the  fighting  fronts,  em- 
ploying them  daily,  involves  about  forty  per 
cent,  replacements  in  aviators,  and  from  one 
hundred  to  two  hundred  per  cent,  replace- 
ments in  machines  per  month.  In  other  words, 
it  takes  six  hundred  aviators  per  month  to  keep 
one  thousand  fighting  continuously,  operating 
day  and  night.  Xot  all  of  these  aviators  are 
killed  or  hurt.  A  large  number  just  "wear 
out"  after  a  few  weeks  or  months  of  intensive 
service,  and  cannot  continue.  They  must  be 
sent  back  to  rest  or  to  be  employed  in  other 
work. 

As  for  machines,  they  are  used  fast  and  in 
large  numbers.  The  anti-craft  guns  are  quite 
accurate  at  heights  of  fifteen  thousand  feet;  and 
speeds  up  to  one  hundred  and  forty  miles  an 
hour  are  necessary  to  maintain  supremacy  in 
the  air.  Landing  such  fast  machines  in  small 
fields  leads  to  damaging  a  great  many. 

However,  when  we  consider  the  tremendous 
value  of  each  aviator,  we  find  that  the  air  service 
is  the  most  im|)ortant  and  economic  branch  of 
the  fighting  forces. 

The  accounts  show  that  in  1918  night  opera- 
tions by  aeroplanes  are  used  more  extensively. 

One  of  the  despatclies  summarizes  some  of 
the  activities  of  the  aviators  as  follows: 

In  moonlight  of  sufficient  brilliance  to  permit  the 
reading  of  a  newspaper,  bombing  planes  and  warplanes 
swarm  out,  carrying  high  explosives,  far  behind  the 
battle  zone.  They  broaden  the  area  of  death  scores  of 
miles,  few  villages  escaping. 

When  the  sun  rises,  the  bombers,  like  prowling 
night  birds,  return  to  their  roost ;  ground  fighting 
speeds  up,  and  scout  fleets,  succeeding  the  bombers, 
fly  low  over  the  clashing  infantry,  harassing  enemy 
columns  and  observing  for  the  artillery. 

One  of  the  reports  of  the  daytime  aerial  op- 
erations reads  as  follows : 


The  enemy's  low-flying  aeroplanes  were  most  per- 
sistent in  their  attack  on  our  infantry  in  the  forward 
areas.  Many  of  these  machines  were  attacked  and 
brought  down  by  our  pilots.  A  total  of  twenty-nine 
hostile  machines  were  brought  down  and  twenty-five 
others  were  driven  down  out  of  control.  Two  enemy 
balloons  were  also  destroyed.  Nine  of  our  machines 
are  missing. 

Our  machines  on  Saturday  carried  out  another  suc- 
cessful raid  on  factories  in  Mannheim.  Nearly  one 
and  a  half  tons  of  bombs  were  dropped,  and  bursts 
were  seen  on  a  soda  factory,  the  railway,  and  docks. 

Several  fires  were  started,  one  of  which  was  of  great 
size,  with  flames  reaching  to  a  height  of  200  feet  and 
smoke  to  5000  feet.  The  conflagration  was  visible 
for  a  distance  of  thirty-five  miles. 

The  weather  Saturday  again  favored  operations, 
and  our  aeroplanes  were  constantly  emj)loyed  in  re- 
connoitering  positions  of  troops,  in  photography  and 
bombing,  and  in  reporting  suitable  targets  for  our 
artillery.  Many  thousands  of  rounds  were  fired  by 
our  pilots  from  low  altitudes  on  hostile  troops  massed 
in  villages  and  in  the  open  continuously  throughout 
the  day. 

More  than  fourteen  tons  of  bombs  were  dropped  on 
enemy  billets,  on  his  high-velocity  guns,  and  on  rail- 
road stations  in  the  battle  area. 

Our  bombing-aeroplanes  were  attacked  by  thirty- 
two  hostile  machines,  and  a  fierce  fight  ensued.  One  of 
the  enemy's  aeroplanes  was  brought  down  in  flames, 
and  another  was  downed,  and  fell  in  the  center  of 
Mannheim.  Five  others  were  driven  down  out  of  con- 
trol. 

Despite  this  severe  combat  and  the  enemy's  heavy 
anti-aircraft  gunfire,  all  our  machines  returned  except 
two.  During  the  night  ten  heavy  bombs  were 
dropped  on  an  important  railway's  bridge  and  works 
at  Konz,  just  south  of  Treves,  in  Germany.  Eight  of 
these  bombs  were  clearly  seen  to  be  bursting  among 
the  railway's  works. 

It  is  stated  officially  that  this  is  only  the  be- 
ginning of  the  intensive  warfare  that  is  to  fol- 
low, one  of  the  great  drives  that  are  to  follow 
each  other  in  quick  succession  hereafter.  We 
must,  therefore,  concentrate  efforts  on  our  air- 
craft program  and  put  all  the  manufacturing 
facilities  now  standing  virtually  idle  in  the 
United  States  to  turn  out  aircraft  and  parts. 

No  time  .should  be  lost  in  adopting  the  plan 
which  is  to  give  the  Allies  the  supremacy  in  the 
air  that  is  so  vital,  as  it  will  decide  the  war  in 
favor  of  the  AHies. 

Henry  Woodhouse. 


INTRODUCTION 


As  President  Wilson  has  repeatedly  pointed 
out,  it  is  most  important  that  the  country  be 
educated  to  its  task. 

The  workers  for  aerial  preparedness  have 
found  in  the  past  that  the  principal  work  was  to 
teach  the  public  the  hnportance  of  aerial  pre- 
paredness, the  tremendous  possibilities  for  the 
employment  of  aircraft  in  connection  with  every 
branch  of  the  army  and  navy,*  and  independ- 
ently. To  teach  the  busy  military  man,  so 
that  he  would  recommend  the  expansion  of  the 
air  service  to  the  legislator,  so  the  legislator 
would  support  the  military  man's  recommenda- 
tions; to  teach  the  engineer,  so  that  he  woidd 
develop  better  aircraft  especially  suited  for  mili- 
tary purposes;  and  the  general  public,  in  order 
to  inspire  j^oung  men  to  volunteer  their  services 
and  men  and  women  to  work  for  the  develop- 
ment of  our  air  forces. 

Now  that  the  world's  strategists  agree  that 
the  present  war  is  to  be  decided  in  the  air,  and 
this  country  has  been  asked  and  has  undertaken 
to  supply  the  thousands  of  aviators  and  tens  of 
thousands  of  machines  needed  to  maintain  aerial 
supremacy  on  the  side  of  the  Allies,  the  great 
demand  is  for  reliable  information  regarding 
the  use  of  aircraft  for  military  purposes. 

Executive  military  officers  who  want  to  know 
the  exact  status  of  military  aeronautics  and  the 
principles  of  aerial  strategy;  students  learning 
military  aviation  who  want  to  know  in  detail  the 
various  phases  of  aerial  warfare;  aeronautic  en- 
gineers and  manufacturers  who  want  to  know 
the  duties  of  aircraft,  in  order  to  design  and 
make  more  efficient  machines;  and  the  average 


patriot  who  wants  to  learn  about  aeronautics  in 
the  hope  of  finding  an  opening  to  employ  his  or 
her  efforts  to  help  the  Government  in  carrying 
the  war  to  a  successful  conclusion,  will  find  in 
this  book  the  publication  they  have  been  looking 
for. 

Another  commendable  point — it  has  many — 
is  the  strong  message  which  the  book  carries  to 
the  American  authorities  and  public.  The  au- 
thor brings  out  once  more  the  importance  of 
air  power  and  urges  full-size  measures.  In  this 
again  every  one  will  agree.  It  is  time  that  we 
shun  half-measures.  The  greatest  of  our  na- 
tional sins  in  aeronautic  matters  has  been  over- 
reliance  on  minimums — minimum  plans,  based 
on  minimum  understanding  of  the  military  and 
aeronautic  situation,  further  weakened  by  mini- 
mum appropriations.  We  have  also  had  some 
minimum  men,  having  minimum  knowledge  and 
experience,  who  did  not  realize,  as  one  must  do 
in  war-times,  the  possible  necessity  of  quick  ex- 
pansion, the  possibility  of  delays,  due  to  trans- 
portation of  materials,  labor  conditions,  mis- 
takes, etc., 

The  one  national  resolution  that  we  ought  to 
make  in  dealing  with  aeronautics  should  be  to 
eliminate  minimums  of  all  kinds  and  adopt 
maximums  in  programs,  men,  appropriations, 
manufacturing  facilities,  etc.  Having  adopted 
maximums,  let  us  add  to  each,  so  as  to  have  a 
substantial  margin  of  safety  to  insure  success 
under  any  circumstances. 

Alan  R.  Hawley, 
President  Aero  Club  of  America. 


CONTENTS 


Chapter  I     The  War  to  be  Decided  in  the 


Air 


Aerial  Supremacy  Must  be  Maintained  Day  and  Night 

Air  Service  the  First  Line  of  Offence  and  Defence — 

Tlie  Use  of  Aircraft  in  Connection  with  Military  Op- 
erations— Aerial  Operations  Independent  of  Land 
Forces— Cooperation  Between  the  Army  and  the 
Navy  in  Conducting  Major  Operations 

Chapter    II     The   Warplane   for   Bombing 

AND  Torpedo  Attacks 9 

The  New  Revolutionary  Weapon  Which  Combines 
Power,  Mobility,  and  Control,  and  Permits  Major 
Aerial  Operations  Against  German  Military  Centers 
and  Naval  Bases — Night  Raids  Can  be  Conducted 
Without  Difficulty — Allies  Have  Never  Had  Enough 
Large  Aeroplanes  With  Which  to  Conduct  Major 
Aerial  Operations — Huge  Warplanes  to  do  at  Long 
Range  What  Huge  Guns  Can  Only  do  at  Short  Range 
— Proportion  of  Bombing  Planes  to  be  Increased — 
Huge  Warplanes  and  Torpedoplanes  Capable  of  Car- 
rying Tons  of  Explosives— Tlie  Marvelous  Giant  Ca- 
proni  Warplane — French  and  British  Bomb-dropping 
Machines — The  Huge  Curtiss  Triplane — Long-distance 
Bombing  Raids  not  New — Long-distance  Allied  Raids 
Into  Enemy  Country  in  tlje  Western  Theatre  of  War 
— Extensive  Damage  Can  be  Done  by  Bombs — Night 
Facilitates  Bombing  at  Close  Range — Need  of  Silencers 
to  Eliminate  Noise  of  Approach — Bombs  and  Bomb- 
dropping  Mechanism— Bomb  Sights — The  Scientific 
Side  of  Bomb  Dropping — Night  Bombing  Requires 
Knowledge  of  Aerial  Navigation  by  Instruments — 
Night  Landing  Lights — Navigation  Lights — The 
Sperry  Automatic  Pilot — Turn  Into  the  Wind  to  Avoid 
Drift — Formation  for  Boml)ing  Raids — Rules  for  For- 
mation Flying — How  1,000  Warplanes  Could  Raid  Kiel 

Chapter   III     Dropping   Bombs   from   Aero- 
planes      31 


Chapter  IV  Battleplanes  AND  Aircraft 
Guns — The  Dominant  Factors  in  Main- 
taining the  Supremacy  of  the  Air  . 
Proportions  of  Different  Types  of  Armed  Aeroplanes 
in  the  Air  Service — Tlie  Five  Fundamental  Factors  in 
Maintaining  Supremacy  in  the  Air — Types  of  Aero- 
planes and  Their  Armament — Avions  de  Chasse  or 
Combat  Machines — Avions  Types  "Corps  d'arme" — 
Used  for  Spotting  Artillery  Fire,  Aerial  Photograph, 
etc. — Pursuit,  or  Combat  Machines — The  Triplane — 
A  Scientific  Solution  of  the  Problem  of  Getting  Speed 
and  High  Factor  of  Safety — Triplane  Safe,  Even  if 
Wing  is  Shot  Away — Battleplanes  That  Collapsed  in 
the  Air — Loss  of  Factor  Safety  Not  Compensated — 
Large  Aerial  Destroyers — Aeroplane  Guns  and  Can- 
non— Large  Aeroplane  Guns — Problems  of  Armoring — 
Vulnerable  Parts  of  the  Aeroplane — Bullets  vs.  High 
Explosive  Shells — Fast  vs.  Slow  Muzzle  Velocity — Re- 
coil ;  a  Solved  Problem — Tactics  in  Air  Duels —  ( 1 )  Air 
Duels  in  Which  Participants  are  Both  Air  Fighters 
Whose  Only  Function  is  to  Keep  the  Sky  Clear  of  En- 
emy Machines — (2)  Air  Duels  Between  Combat  Ma- 
chines and  Armed  Photographing,  Spotting,  or  Bomb- 
ing Machines — (3)  Air  Duels  Between  Large  Armed 
Aeroplanes — Formation  in  Air  Fighting — Lamp  Sig- 
nals for  Use  of  Leaders  of  Formations — Offensive 
Fighting  Tactics — Thorough  Knowledge  of  Weapons  is 
Requir^ 


39 


PAGE 

Chapter  V     The   Fundamental  Principles 

OF  Aerial  Combat 63 

Chapter  VI     Directing  Artillery  Fire  by 

Night  and  Day  Signaling  to  and  from 

Aircraft "^^ 

Methods  and  Codes  Used  for  Communicating  From  and 
to  Aircraft — Tlie  Observer's  Special  Map — Signaling 
With  Very's  Lights — Kite  Balloons  for  Spotting  Artil- 
lery Fire — The  Dubilier-GoU  Semi-Radio  Telephone 
System  for  Captive  Balloons — Signaling  Between  Air- 
craft— Cooperation  Between  Balloons  and  Artillery 

Chapter  VII     Kite  Balloons  the  Eyes   of 

the   Artillery 81 

Maneuvering — Camp  Equipment  of  a  Kite  Balloon 
Unit — An  Artillery  Captain's  Experience — Personnel 
of  Kite  Balloon  Company — Preparations  for  Ascen- 
sion— What  You  Can  See  from  a  Kite  Balloon — Aero- 
plane vs.  Captive  Balloon — A  Leap  Into  Space  from 
a  Kite  Balloon — A  Curious  Maneuver — A  Drama  at  the 
End  of  a  Cable 

Chapter  VIII  Aero  Photography  ...   91 

Tliousands  of  Miles  of  Photographic  Maps — Twenty  Per 
Cent  of  Aeroplanes  at  the  Front  Used  for  Aerial  Pho- 
tography— The  Aerophotographic  Organization  of  an 
Army — Seven  Aeroplane  Bombs  Photographed  Soon 
After  Release  by  the  French  Aviator  That  Released 
Them  on  a  German  Plant — Aeroplane  Photography 
That  Shows  Minutest  Details  of  a  Factory  Cliimney 
Being  Repaired — A  Photographic  Officer  Should  be  Fa- 
miliar With  the  Following  Technical  Subjects — Cam- 
eras and  Fittings — Loading  of  Plates — Negative  Devel- 
oping— Finish  of  Work — A  Squadron  Photographic 
Non-commissioned  Officer  With  His  Three  Men  Should 
be  Familiar  With  the  Following — Science  of  Aeropho- 
tography  Still  Young — Essentials  in  Aerophotographs 
— Relative  Elevations  Hard  to  Show — Interpreting 
Photographs  Requires  Skill — Problems  of  Aerophotog- 
raphy — Different  Types  of  Cameras — Possible  Troubles 
in  Taking  Aero  Photographs  and  Their  Remedy 

Chapter  IX     Reconnaissance  and  Contact 

Patrol  Work  by  Aeroplane  ....      Ill 

Five  Types  of  Reconnaissance — Procedure  in  Issuing 
Orders  "for  Reconnaissance — How  Reconnaissance  Aero- 
planes are  Guarded  and  Protected — Protecting  Recon- 
naissance Machines — Navigation  Rules  for  Reconnais- 
sance— Pilots  and  Observers — Aircraft  Report  Diary 
Contact   Patrol    (Aeroplanes   De   Liason) 

Chapter  X     Night  Flying 126 

Zeppelin  Raids  Forced  Aeroplane  Night  Flying — Long- 
distance Bombing  Night  Raids — Aeroplanes  Cannot 
be  Seen  One  Hundred  Feet  Away — The  Operation  of 
Aeroplanes  by  Night — Lighting  the  Aerodromes — The 
"Honig  Circles"  Signals  for  Night  Flyers — Lights  for 
Night  Landing  Grounds — Returning  from  Night 
Flights — The  Signals — Lighting  Equipment  of  Aero- 
planes— Instruments  Painted  with  Luminous  Com- 
pounds— Adventures   in   Night   Flying 


Chapter  XI     Radio  for  Aeroplanes 


139 


CONTENTS 


Chaptee  XII     Military  Aerostatics 

Dirigible  Balloons — Rigid,  S«>mi-Ripid.  and  \on-Rigid 
Dirigibles — Military  Observation  Balloons — Employed 
at  Nght  as  Well  as  in  the  Daytime — For  Directing 
Artillery  Fire — Hydrogen  Supply  and  the  "Nurse" — 
The  Windlass — Free  Balloon  Training  Necessary — The 
Free  Balloons — Synopsis  of  the  Course  of  Training  at 
United   States   Army   Balloon   School 

Chapter  XIII     Hydrogen  for  Military  Pur- 
poses         


page 
157 


167 


Proportii-s  of  Hydrogen — Vitriol  Process — Electrolytic 
Metiiod — Silicol  Process — Iron  Contact  Process — Alu- 
minum Caustic  Soda  Process — Hydrolithe — Hydroge 
nite — Hydrogen  from  Water — Gas — Aluminum  Potas- 
sium Cyanide  Process — Acetylene  Process — Iron  and 
Water  Process — Silico-Acetylene  Process — Decarbura- 
tion  of  Oils 

Chapter  XIV  Training  Aviators  for  the 
United  States  Army  ;  Home  and  For- 
eign Service 

Schools  of  Military  Aeronautics  (Ground  Schools)  — 
Instruction  in  the  Junior  Wing — Instruction  in  the 
Senior  Wing — Training  at  Army  Aviation  Schools — 
Tests  for  an  Aviator's  Certificate — Spherical  Balloon 
Pilot's  Certificate — Dirigible  Balloon  Pilot's  Certifi- 
cate— Aviator's  Certificate — Hydroaeroplane  Pilot's 
Certificate — United  States  Army  Preliminary  Flying 
Test — United  States  Army  Reserve  Military  Aviator 
Test 

Chapter  XV'  Regulations  for  Uniforms  of 
U.  S.  Aeronautic  Personnel 

Uniform  Specifications — Coats,  Aviator,  Anti-sinking — 
Face  Mask,  Aviators — Flying  Suit — Gloves,  Aviator, 
Winter — Gloves,  Aviator,  Summer — Goggles — Helmet, 
Aviators,  Summer — Helmet,  Aviators,  Winter — Avia- 
tion Service — Mufflers — Shoes,  Aviator,  Winter — Boots, 
Rubber,  Wading  (Wading  Pants) — Breeches,  Winter, 
Motorcycles — Insignia,  SU-eve — Changes  in  Regulations 
for  the  Uniforms  of  the  United  States  Army,  1014, 
to  Cover  Aviation — Uniforms  of  the  United  States 
Army — Officers — Enlisted    Men 

Chapter  XVI     Aeronautic  Maps 

Five  Types  of  Aeronautic  Maps — Tlie  Map  With  Pho- 
tographic Reproduction  of  Route  and  Information  Re- 
garding Prevailing  Winds — The  War  Prevented  an 
International  Convention  on  Aeronautic  Cartography 
— Existing  Aeronautic  Maps  are  the  Result  of  Work 
by  Aero  Clubs 

Chapter  XVII     History  of  United  States 

Army  Aeronautics 

Aeroplanes  of  All  Types  Purchased  by  the  Signal  Corps 
— The  Mexican  Campaign   Found  the  United  States 


179 


190 


197 


204 


PAQB 


Army  Unprepared  Aeronautically — Aircraft  Board 
Created— The  $1,0.32,294,260  Army  Air  Program— Long 
Delay  in  Extending  Plans  and  €retting  Appropria- 
tions Causes  Trouble 

Chapter    XVIII     The   Evolution   of   Mili- 


tary Aviation 


222 


Signal  Corps  Specification,  No.  486 — General  Condi- 
tions of  French  Military  Competition  of  1910-1911 — 
The  Kaiser's  Prize  for  a  Motor  Competition — Aero- 
planes First  Used  for  Military  Purposes  in  the  Italian- 
Turkish  War — French  Aviation  Developed  by  Public 
Interest — Firing  Guns,  Dropping  Large  Bombs,  and 
Two-engined  Aeroplanes  Once  Considered  Impossibil- 
ities— British  Army  Tests  for  Aeroplanes  in  1914 — 
Aeronautics  at  the  Outbreak  of  the  War — Advent  of 
Large  Warplanes  in  1917  Permitted  Conducting  Major 
Aerial  Operations — The  United  States  Lagged  Behind 
for  Seven  Years — Aero  Club  of  America's  Monumental 
Work  in  Developing  Our  Aerial  Forces — America's  En- 
try Into  the  War  Brings  Decision  to  Concentrate  Ef- 
forts to  Strike  Germany  Tlirough  tlie  Air — Tlie  Prob- 
lem of  Delivering  Aeroplanes  to  Europe — British  Air 
Ministry  Created 

Chapter    XIX     Some    Problems    in    Aero- 
plane  Construction 

Military  Functions  of  Aeroplanes— Some  Problems  in 
Construction — Propeller  Stresses — Suggestions  for  Im- 
provements in  Design 

Chapter  XX     Methods  of  Measuring  Air- 
craft Performances 

Aeroplane    Testing — Speeds 


245 


259 


Chapter     XXI     The     Sperry     Automatic 

Pilot 269 

Incorporating  a  Gyroscopic  Reference  Plane  and  Clin- 
ometer for  Aeroplanes — Its  Application  for  Military 
Purposes 

Chapter  XXII     The  Case   for  the  Large 

Aeroplane 274 

Aerodynamical  Bases  of  Comparison — The  Effect  of  an 
Increase  in  Size  on  the  Structural  Weight  of  Aero 
planes — The  Effect  of  an  Increase  in  Siz.e  Upon  an 
Aeroplane's  Performance — Tlie  Large  Machine  from  the 
Pilot's    Standpoint 

Chapter  XXIII  Every  Military  Aviator 
Ought  to  Know  What  His  Own  and  the 
Enemy's  Machine  Can  do  and  How  They 
Look 282 

Index 293 


TEXTBOOK 

OF 

MILITARY  AERONAUTICS 


A  squadron  of  Gotha  biplanes  which  raided  I.ondon  in  full  daylight  on  July  7th,  1917.     They  were  equipped  with  two  260  horse- 
power Mercedes  engines  and  carried  800  pounds  of  explosives.     Forty   people   were   killed   and   19-1   injured. 


CHAPTER  I 


THE  WAR  TO  BE  DECIDED  IN  THE  AIR 


This  war  is  to  be  decided  in  favor  of  the  side 
which  maintains  its  supremacy  in  the  air 
through  having  the  largest  number  of  efficient 
aircraft  and  airmen. 

The  world's  strategists  agree  on  this  point, 
and  the  struggle  for  command  of  the  air  is  rag- 
ing. 

The  air  service  is  the  balance  of  power,  a 
most  marvelous  power  combined  with  unlimited 
mobility  and  control  to  such  a  tremendous  ex- 
tent that  it  makes  of  the  aircraft  a  new  arm  of 
revolutionary  potentiality. 

Aerial  Supremacy  Must  Be  Maintained 
Day  and  Night 

Command  of  the  air  means  maintaining  su- 
premacy in  the  air  by  day  and  by  night. 

Holding  supremacy  of  the  air  during  the  day- 
time avails  little  if  the  enemy  has  supremacy  of 
the  air  at  night,  and  vice  versa. 

Aerial  supremacy  at  night  can  be  main- 
tained by  conducting  extensive  night-bombing 


operations  against  German  military  centers, 
military  supply  bases,  and  railroads,  and  by  sub- 
stantial naval  aerial  operations,  also  at  night, 
against  the  German  fleet  and  U-boat  bases, 
striking  the  ships  of  the  German  fleet  with  tor- 
pedoes launched  from  torpedoplanes,  and  the 
U-boats  and  their  bases  with  bombs  dropped 
from  the  air. 

Aerial  supremacy  during  the  daytime 
means  guarding  the  different  fronts  with  an 
overwhelming  number  of  aeroplanes  of  the 
fighting  type,  as  well  as  with  the  types  used  for 
regulating  artillery  fire,  for  aerial  photography, 
for  scouting,  and  in  connection  with  infantry 
and  cavalry  operations;  and  by  short,  daylight, 
bombing  expeditions. 

Major  aerial  operations,  supported  by  ener- 
getic military  operations  on  land  and  naval 
operations  at  sea,  could,  as  Admiral  Fiske  has 
pointed  out  repeatedly,  in  a  comparatively  brief 
period  of  time  destroy  Germany's  strength  as 
nothing  else  can.  They  could  do  more  than 
the  addition  of  a  million  men  on  land  and  five 


TEXTBOOK  OF  ^IILITARY  AERONAUTICS 


Caproni  warplanc — one  of  the  largest  warplanes  In  the  world. 


naval  squadrons  at  sea  could  accomplish:  be- 
cause, as  is  generally  admitted,  additional  men 
would  avail  little  against  the  entrenched  Ger- 
man lines.  Capturing  lines  at  present  involves 
going  through  many  lines  of  trenches ;  and  that 
involves  lengthy  preparatory  activities. 

The  same  thing  is  true  at  sea;  ships  and 
men  can  do  little  against  the  protected  German 
fleet,  because  of  the  miles  of  mines  and  other 
defenses  which  guard  it. 

As  Admiral  Fiske  has  pointed  out  in  the 
"Textbook  of  Naval  Aeronautics,"  the  large 
warplane  combines  power,  mobility,  and  control 
as  no  other  weapon  does,  and  permits  the  quick 
concentration  on  any  given  point  of  large 
jnasses  of  explosives. 

•  Aircraft  can  flj'  over  all  obstructions,  both  at 
sea  and  on  the  land,  as  though  they  did  not  ex- 
ist. True,  during  daylight  squadrons  of  Ger- 
man battleplanes  and  hundreds  of  German  anti- 
aircraft guns  would  attempt  to  prevent  the 
progress  of  the  Allies'  raiding  forces,  which 
would  involve  casualties,  although  only  a  frac- 
tion of  the  casualties  that  result  every  day  in  the 
least  important  land  operations. 

Air  Service  the  First  Line  of  Offense  and 
Defense 

The  air  service  has  become  the  first  line  of  of- 
fen.se  and  defense.  Every  military  operation  is 
preceded  by  aerial  operations  which  include: 


(1)  Bombing  the  enemy's  bases,  destroyin<)- 
railroads,  trains,  and  enemy  material. 

This  is  done  with  bombing  aeroplanes,  self- 
sufficient,  or  protected  by  fighting  machines. 
(See  chapters  on  "Battleplanes  and  Aircraft 
Guns"  and  "Warplanes  for  Bombing  and  Tor- 
pedo Attacks.") 

(2)  Fighting  hostile  aeroplanes,  preventing- 
them  from  making  aerial  reconnaissance  or  tak- 
ing photographs  of  one's  positions,  thus  direct- 
ing the  fire  of  their  artillery,  etc.  Small, 
fighting  aeroplanes  are  used  for  this  purpose. 
(See  chapter  on  "Battleplanes  and  Aircraft 
Guns.") 

(3)  Reconnoitering.  Determining  the 
strength  of  the  enemy,  its  composition,  disposi- 
tions, and  probable  intentions.  Aeroplanes  of 
different  types  are  used  for  this  purpose. 

(4)  Photographing  the  enemy  ])ositions. 
These  photogi-aphs,  by  giving  accurate  details 
of  the  enemy's  position,  permit  conducting  op- 
erations based  on  exact  information,  and  there- 
fore afl'ord  the  greatest  chance  for  success. 
Aeroplanes  and  kite-balloons  are  used  for  this 
purpose. 

(5)  Directing  artillery  fire.  This  is  done 
with  both  aeroplanes  and  kite-balloons,  and  has 
become  an  exact  science. 

(6)  Contact  patrol.  Coordinating  the  ac-, 
tivities  of  the  different  arms  during  attacks.  Tn| 
this  role  the  aviator  becomes  the  master-mind 
that  watches  over  everv  movement  of  the  eneiiiv. 


THE  WAR  TO  BE  DECIDED  IN  THE  AIR 


as  well  as  of  his  own  forces,  and  transmits  to  his 
own  forces  information  regarding  the  advance, 
retreat,  and  other  movements  of  the  enemy,  di- 
recting the  sending  of  reinforcements  to  the 
weak  or  threatened  points,  and  controlling  the 
fire  of  the  machine-gun  batteries  as  well  as  of 
the  artillery.  Aeroplanes  of  different  types 
are  used  for  this  purpose. 

(7)  Cooperating  with  the  infantry  and  other 
arms  in  taking  trenches,  by  flj'ing  low  over  the 
trenches  and  attacking  the  enemy  with  machine- 
guns.  Different  types  of  one-  or  two-passen- 
ger aeroplanes  are  used. 

(8)  Cooperating  with  the  artillery  and  other 
arms  by  attacking  the  crews  of  hostile  batteries 
with  machine-guns.  Different  types  of  one-  or 
two-passenger  aeroplanes  are  used  for  this  pur- 
pose. 

(9)  Making  attacks  with  bombs  or  gims 
against  land  forces,  to  engage  the  enemy  and 
distract  his  attention  from  ope^-ations  which  are 
about  to  be  conducted ;  in  other  words,  perform- 


ing the  functions  of  cavalry,  which  has  been 
used  but  httle  along  the  western  front. 

(10)  Conducting  aerial  attacks  from  the 
rear  with  bombs  and  machine-guns  against 
enemy  land-forces,  to  relieve  the  pressure  being 
brought  by  the  enemy's  forces  against  any  one 
point,  or  to  wear  down  the  strength  of  the  ene- 
my's land-forces.  Different  types  of  battle- 
planes are  used  for  this  purpose. 

(11)  Preventing  reinforcements  from  reach- 
ing the  enemy,  by  flying  far  into  the  enemy 
lines,  watching  for  trains  and  attacking  them 
with  bombs  and  machine-guns.  Different 
types  of  battleplanes  are  used  for  this  purpose. 

The  Use  of  Aircraft  in  Connection  with 
Military  Operations 

The  use  of  aircraft  in  connection  with  mili- 
tary operations  has  become  so  extensive  that  it 
may  be  said  that  the  air  service,  cooperating 
with  the  land-forces,  is,  in  itself,  an  aerial  army, 


J 


A  remarkable  pliotojiraph  of  the  capture  of  German  trenrhes  by  the  French  infantry  on  the  Somme.  This  photograph  was  taken 
by  a  French  aviator  at  a  height  of  only  500  feet.  The  trench  in  the  left  foreground,  named  the  Guillaume  Trench,  had  formed  the 
German  front  line.  Slanting  up  to  it  from  the  right-hand  corner  is  a  communication-trench,  by  which  French  reinforcements  are  seen 
arriving.     Shell  craters  are  seen  everywhere. 


6 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Air  craft  can  go  over  all  obstructions  which  stop  the  pnif^rc^s  of  .snii)s  and  armies.  How  conipktc  is  its  supremacy  may  be  seen 
from  the  above  photograph,  taken  from  an  Italian  military  aeroplane  (part  of  which  is  shown  in  the  photograph)  while  crossing 
the  Alps.     Italian  aviators  connected  with  the  Trentin  Army  flew  daily  under  such  conditions. 


the  aeroplanes  performing  the  function  of  cav- 
alry, artillery,  and  infantry. 

General  Haig,  commander-in-chief  of  the 
British  forces  in  France,  in  his  official  reports 
has  stated  repeatedly  that  the  employment  of 
aeroplanes  in  connection  with  military  opera- 
tions is  practically  unlimited. 

In  one  of  his  latest  reports  he  speaks  of  the 
work  of  the  Royal  Flying  Corps  as  follows : 

"In  this  combination  between  infantry  and 
artillery  the  Royal  Flying  Corps  jAayed  a 
highly  important  part.  The  admirable  work 
of  this  Corps  has  been  a  very  satisfactory  fea- 
ture of  the  battle.  Under  the  conditions  of 
modern  war  the  duties  of  the  Air  Service  are 
many  and  varied.  They  include  the  rcgu'ation 
and  control  of  artillery  fire  by  indicating  targets 
and  observing  and  reporting  the  results  of 
rounds;  the  taking  of  photographs  of  enemy 
trenches,  strong  points,  battery  positions,  and 
the  effect  of  bombardments;  and  the  observa- 
tion of  the  movements  of  the  enemy  beliind  his 
lines. 

"The  greatett  ikUl  and  daring  has  been 
ihown  in  the  performance  of  all  these  duties,  as 


well  as  in  bombing  expeditions.  Our  Air  Serv- 
ice has  also  cooperated  with  our  infantry  in  their 
assaults,  signaling  the  position  of  our  attacking 
troops  and  turning  machine-guns  on  the  enemy 
infantry  and  even  on  his  batteries  in  action. 

"Not  only  has  the  work  of  the  Royal  Flying 
Corps  to  be  carried  out  in  all  weathers  and 
under  constant  fire  from  the  ground,  but  fight- 
ing in  the  air  has  now  become  a  normal  pro- 
cedure, in  order  to  maintain  the  mastery  over 
the  enemy's  Air  Service.  In  these  flights  the 
greatest  skill  and  determination  have  been 
shown,  and  great  success  has  attended  the  ef- 
forts of  the  Royal  Flying  Corps.  I  desire  to 
point  out,  however,  that  the  maintenance  of 
7nastery  in  the  air,  xchich  is  essential,  entails  a 
constant  and  libera!  supply  of  the  most  up-to- 
date  machines,  without  which  even  the  most 
skilful  pilots  cannot  succeed. 

"The  style  of  warfare  in  which  we  have  been 
engaged  offered  no  .scope  for  cavalry  action, 
with  the  exception  of  the  one  instance  already 
mentioned,  in  which  a  small  body  of  cavalry 
gave  useful  assistance  in  the  advance  on  High 
Wood." 


THE  WAR  TO  BE  DECIDED  IN  THE  AIR 


Aerial  Operations   Independent  of 
Land-Forces 

Aerial  operations  independent  of  the  land- 
forces  are  increasing  in  number  and  extent. 
The  advent  of  large  battleplanes  with  a  flying 
radius  of  close  to  1000  miles,  and  capable  of 
carrying  one  ton  or  more  of  explosives,  will  in- 
crease the  extent  of  bombing  operations. 

It  is,  roughly,  between  450  and  500  miles 
from  Great  Britain  to  Kiel,  Wilhelmshaven, 
and  Helgoland.  It  is  less  than  300  miles  from 
the  Allies'  lines  to  Essen  and  Diisseldorf,  and 
it  is  less  than  100  miles  from  the  main  Allied 
aeronautic  bases  to  Zeebrugge  and  Ostend, 
which  are  important  bases  for  U-boats  and 
German  destroyers. 

Details  regarding  the  types  of  warplanes 
used  for  bombing  and  major  operations  are 
given  in  the  chapter  on  "The  Warplane  for 
Bombing  and  Torpedo  Attacks." 

Cooperation  Between  the  Army  and  the 

Navy  in  Conducting  Major 

Operations 

As  pointed  out  in  the  "Textbook  of  Naval 
Aeronautics,"  it  is  difficult  to  define  the  lines  of 
demarcation  where  the  navy  ceases  to  operate 


and  the  army  begins  to  operate,  and  vice  versa. 
The  Allies  have,  very  wisely,  combined  their 
aerial  resources  to  conduct  major  aerial  opera- 
tions. 

It  would  be  hard  to  figure  out  under  whose 
jurisdiction  a  raid  should  be  conducted  which 
involves  flying  over  land  and  sea;  therefore  all 
lines  of  demarcation  have  been  wiped  out  in  so 
far  as  major  operations  are  concerned,  the 
bombing  squadrons  usually  including  army  and 
naval  aviators  of  two  or  three  of  the  allied  na- 
tions. It  is  to  be  expected,  therefore,  that 
army  aviators  will  be  called  upon  to  participate 
in  operations  in  which  their  aeroplanes  will 
carry  torpedoes,  to  be  used  in  attacks  against 
the  German  fleet,  just  as  naval  aviators  have 
been  called  upon  to  conduct  bombing  operations 
against  German  military  bases,  as  in  the  case  of 
the  raids  on  Essen  and  Obendorf . 

In  the  United  States  the  army  has  charge  of 
the  coast  defense ;  therefore  the  army  air  service 
uses  land  and  water  aeroplanes,  airships,  and 
captive  balloons. 

The  functions  of  aircraft  for  coast  defense 
are: 

( 1 )  For  reconnaissance,  patrolling  the  coasts, 
looking  for  hostile  ships  of  all  types,  enemy  sub- 


A  French  Nieuport  fighting  aeroplane  photographed  as  it  was  passing  another  military  aeroplane  in  midair. 


8 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


marine  bases,  and  mines.  Aeroplanes,  large 
and  small,  land  and  water,  and  dirigibles  are 
used. 

(2)  To  prevent  the  landing  of  enemy  forces 
by  attacking  the  hostile  ships  and  transports 
with  torpedoes,  guns  of  large  caliber,  and 
bombs.  Aeroplanes,  land  and  water,  and  dirig- 
ibles are  used. 

(3)  To  attack  hostile  bombarding  and  block- 
ading ships  with  torpedoes,  guns,  and  bombs. 
Aeroplanes,  land  and  water,  and  dirigibles  are 
used. 

(4)  To  direct  and  spot  the  fire  of  coast  de- 
fense batteries.  Aeroplanes,  land  and  water, 
dirigibles,  and  captive  balloons  are  used. 

(5)  To  fight  off  enemy  aircraft,  preventing 


them  from  gathering  and  transmitting  informa- 
tion about  the  location  and  disposition  of  our 
coast  defenses.  Aeroplanes  and  dirigibles  are 
used. 

(6)  To  transmit  confidential  information  be- . 
tween  militarj'  stations.     Aeroplanes  and  dirig- 
ibles are  used. 

(7)  To  convoy  troopships,  merchantships  and 
army  transports  on  coastwise  trips.  Aero- 
planes, land  and  water,  and  dirigibles  are  used. 

(8)  To  locate  mine-fields  and  assist  trawlers 
in  destroying  mines.  Aeroplanes,  dirigibles, 
and  captive  balloons  are  used. 

(9)  To  serve  as  the  "eyes"  in  planting  mines. 
Captive  balloons,  dirigibles,  and  aeroplanes  are 
used. 


The  effect  of  a  bomb  dropped  on  an  aeiodioiiie  at  ftaionica  by  a  Cjeniian  aeroplane.     It  just  missed  hitting  the  hangars  and  garage. 


CHAPTER  II 

THE  WARPLANE  FOR  BOMBING  AND  TORPEDO  ATTACKS 

The   New   Revolutionary   Weapon   Which   Combines  Power,   Mobility,   and  Control,   and 
Permits  Major  Aerial  Operations  Against  German  Military  Centers  and  Naval  Bases 


It  is  generally  agreed  that  the  most  effective 
and  quickest  way  of  achieving  victories  of  de- 
cisive importance  over  Germany  is : 

( 1 )  By  conducting  substantial  bombing  oper- 
ations against  German  military  centers,  military 
supply  bases,  and  railroads; 

(2)  By  conducting  substantial  aerial  opera- 
tions against  the  German  fleet  and  U-boat  bases, 
striking  the  Gei-man  fleet  with  torpedoes 
launched  from  torpedoplanes  and  the  U-boats 
and  the  bases  with  bombs  dropped  from  the  air, 
as  well  as  with  shots  from  aeroplane  guns  of 
large  caliber. 

Such  major  aerial  operations,  supported  by 
energetic  military  operations  on  land,  and  naval 
operations  at  sea,  could,  as  Admiral  Fiske  has 
pointed  out  repeatedly,  in  a  comparatively  brief 
period  of  time  destroy  Germany's  strength  as 
nothing  else  can.  They  could  do  more  than 
the  addition  of  a  million  men  on  land  and  five 
naval  squadrons  at  sea,  because,  as  it  is  gener- 


ally admitted,  additional  men  could  do  but  lit- 
tle against  the  entrenched  German  lines.  Cap- 
turing lines  at  present  involves  going  through 
many  lines  of  trenches,  and  that  involves 
lengthy  preparatory^  activities. 

The  same  thing  is  true  at  sea;  ships  and  men 
can  do  but  little  against  the  entrenched  German 
fleet,  because  of  the  miles  of  mines  and  other 
defenses  which  protect  the  German  fleet. 

As  Admiral  Fiske  has  pointed  out  in  the 
"Textbook  of  Naval  Aeronautics,"  the  large 
warplane  combines  power,  mobility  and  control 
as  no  other  weapon  does,  and  permits  the  quick 
concentration  on  any  given  point  of  large 
masses  of  explosives. 

Aircraft  can  fly  over  all  obstructions,  both  in 
the  sea  and  on  the  land,  as  though  they  did  not 
exist.  Tnie,  during  daylight,  squadrons  of 
German  battleplanes  and  hundreds  of  German 
anti-aircraft  gims  would  attempt  to  prevent  the 
progress   of  the  Allies'   raiding   forces,  which 


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would  involve  casualties — although  only  a  frac- 
tion of  the  casualties  that  result  every  day  in 
the  least  important  land  operations. 

Night    Raids    Can    Be    Conducted    Without 
Difficulty 

A  thousand  aeroplanes  could  flj'  from  the 
nearest  Allied  bases  to  the  German  bases  at 
Kiel  and  Wilhehnshaven,  or  to  Essen,  Berlin, 
and  other  German  military  centers,  almost  un- 
seen. 

At  night  aeroplanes  can  hardly  be  seen  a  hun- 
dred feet  away  by  other  aeroplanes,  and  it  is  a 
most  difficult  thing  for  searchlights  to  locate 
them  in  the  sky.  Under  the  best  weather  con- 
ditions and  a  fairly  clear  night,  a  squadron  of 
Allied  aeroplanes  started  from  Salonica  re- 
cently to  bomb  the  German  lines.  They  ar- 
rived over  the  German  lines,  and  were  surprised 
when  all  at  once  the  lights  of  the  German  aero- 
drome were  lighted.  The  Allied  aviators 
dropped  their  bombs  and  returned  to  their  own 
aerodrome — to  find  that  German  aviators  had 
in  the  meantime  bombed  the  Allied  lines.  The 
squadrons  had  passed  each  other  en  route,  but 
neither  side  had  sighted  the  other.  In  each 
case  the  officers  in  charge  of  the  aerodromes 
lighted  the  aerodromes  when  they  heard  the 
noise  of  motors,  thinking  that  their  aviators 
were  returning  from  their  bombing  raid.  In 
scores  of  cases  single  aeroplanes  or  fleets  of  five 


or  more  aeroplanes  have  carried  on  bombing 
raids  during  the  night  without  being  seen  by 
Germans.  Therefore,  the  solution  of  striking 
Germany  through  the  air  rests  in  night  raids. 

Allies  Have  Never  Had  Enough  Large 

Aeroplanes  with  Which  to  Conduct 

Major  Aerial  Operations 

Neither  the  Allies  nor  the  Teutons  have  had 
a  sufficient  number  of  large  aeroplanes  to  per- 
mit them  to  conduct  major  aerial  operations 
against  the  other  side.  While  there  are  now 
thousands  of  aeroplanes  employed,  whereas 
there  were  only  a  few  hundred  in  the  beginning 
of  the  war,  the  use  of  aeroplanes  has  been  so 
greatly  extended,  and  they  are  used  for  so  many 
miportant  purposes  in  connection  with  military, 
coast  patrol,  and  naval  operations,  that  it  has 
been  impossible  to  accumulate  the  number  of 
aeroplanes  recjuired  for  major  aerial  operations. 

It  is  also  true  that  until  recently  there  were 
not  available  the  types  of  large  aeroplanes  re- 
quired for  long  distance  bombing  or  torpedo 
launching  operations. 

Huge  Warplanes  to  Do  at  Long  Range  What 
Huge  Guns  Can  Only  Do  at  Short  Range 

Major  R.  Perfetti,  the  head  of  the  Special 
Italian  Commission  for  Aeronautics  in  the 
United  States,  brought  to  the  attention  of  the 


Tlie  Gcriiinii  Gotliii  warpliinc. 


THE  WARPLANE  FOR  B03IBIXG  AND  TORPEDO  ATTACKS 


11 


When  the  "Emergency  Air  Fleet"  Crosses  the  Rhine! 


Allied  military  authorities  the  fact  that  huge 
warplanes  can  do  at  long  range  what  huge  guns 
can  only  do  at  short  range.  He  pointed  out 
that,  just  as  reducing  the  fortresses  and  posi- 
tions which  were  supposed  to  be  invulnerable 
was  done  by  concentration  of  the  fire  of  many 
huge  guns,  the  reducing  of  distant  military  and 
naval  bases  can  be  accomplished  by  the  drop- 
ping of  tons  of  explosives  simultaneously  by 
hundreds  of  warplanes. 

This  was  an  obvious  truth,  which  heretofore 
could  only  be  figured  out  theoretically,  but  not 
proven  in  practice,  because  of  the  lack  of  war- 
planes  powerful  enough  to  carry  tons  of  explo- 
sives. jSIajor  Perfetti  could  state  it  as  a  tested 
and  proven  truth,  because  Italy  has  the  huge 
warplanes  needed  for  these  operations,  and  has 


been  using  them  on  a  limited  scale  in  her  oper- 
ations against  the  Austrians  over  the  moun- 
tains and  across  the  Adriatic  Sea. 

If  the  United  States  takes  steps  promptly  to 
build  thousands  of  these  huge  triplanes,  it  is 
possible  that  substantial  deliveries  will  begin  to 
be  made  in  six  months,  making  it  possible  to 
figure  on  aerial  operations  against  the  German 
naval  and  military  bases  next  spring  and  sum- 
mer.    Nothing  else  affords  such  possibilities. 

Proportion  of  Bombing  Planes  to  Be 
Increased 

Heretofore,  owing  to  limited  production,  the 
proportion  of  bombing  planes  to  the  number  of 
aeroplanes  used  has  been  only  about  ten  per 
cent.     Twenty  per  cent,  have  been  small,  fast 


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A   British  aviator  throwing  a  bomb. 

fighting  machines  to  fight  enemy  aviators  en- 
gaged in  similar  work,  or  in  photographing,  di- 
recting artillery  fire,  reconnoitering,  etc. 

Now  that  the  United  States  has  entered  the 
war,  and  has  mobilized  manufacturing  resources 
to  the  point  where  a  program  to  munufacture 
100,000  aeroplanes  could  be  completed  in  three 
years,  the  proportion  of  bombing  planes  can  be 
increased  by  the  addition  of  thousands  of  huge 
bombing  warplanes,  many  of  which  can  be  man- 
ufactured in  America,  the  Italian  Government, 
like  the  British  and  French  Governments,  hav- 
ing offered  to  cooperate  with  the  United  States 
Government. 

Huge   Warplanes    and   Torpedoplanes   Cap- 
able of  Carrying  Tons  of  Explosives 

The  Allies  now  have  huge  warplanes  and  tor- 
pedoplanes capable  of  carrying  from  two  to 
three   tons   of   explosives   or   torpedoes.     The 


gigantic  Caproni  torpedoplanes  permit  aerial 
o])erations  from  any  of  the  Allied  bases  to  any 
German  naval  or  military  base  and  return — 
with  substantial  reserve  fuel. 

The  Curtiss  triplane  air-cruiser,  while  handi- 
capped by  the  heavy  flying-boat  hull,  is  also  a 
good  possibility.  The  twin-motored  Handley- 
Page  biplane  and  the  new  three-motored  Gal- 
laudet  seaplane  are  among  other  possibilities 
for  long-distance  aerial  raids. 

The    Marvelous    Giant    Caproni    Warplane 

Italy  leads  in  types  of  bombing  and  gun-car- 
rying aeroplanes. 

The  following  are  some  of  the  most  important 
types  of  Italian  aeroplanes,  types  which,  if 
built  by  thousands,  will  make  it  possible  for  the 
Allies  to  conduct  the  major  aerial  operation 
a'?ainst  Germany  which  is  to  ensure  her  down- 
fall: 

(1)  The  largest  Caproni  triplane.  This  re- 
markable warplane  is  equipped  with  three  large 
h.p.  Fiat  motors.  The  details  about  this  ma- 
chine are  kept  secret,  but  it  is  known  that  the 
machine,  as  a  whole,  follows  the  characteristics 
of  the  Caproni  warplanes.  This  machine, 
judged  by  the  smaller  types,  must  carry  about 
five  tons  of  explosives  and  fuel  for  twelve  hours, 
at  a  speed  of  about  eighty  miles  an  hour. 

(2)  The  small  bombing  type  Caproni  tri- 
plane. This  machine,  which  is  illustrated  here- 
with, is  a  triplane,  with  two  fuselages,  equipped 
with  three  Fiat  or  Isotta-Fraschini  motors,  two 
in  front  fitted  with  one  propeller  respectively, 
and  one  in  the  rear,  also  fitted  with  one  pro- 
peller.    Each  of  the  engines  is  independent  of 


Italian  Battleplane..     From  left  to  rl.ht:  th-  C.pronl   triplane.  .•,uipp,-.l  v.i.1.  .h"-^  •-.>  '< 


tors. 


THE  WARPLANE  FOR  BOMBING  AND  TORPEDO  ATTACKS 


13 


The  Italian  Caproni  warplane  returning  from  a  flight. 


the  others,  so  that  if  two  of  the  engines  should 
stop,  the  machine  could  still  keep  in  the  air  with 
the  power  of  one  motor. 

(3)  The  bombing  type  Caproni  biplane. 
This  type  of  machine  is  most  remarkable  for 
its  speed.  It  is  equipped  with  three  Fiat  or 
Isotta-Fraschini  motors  of  200  h.p.,  and  three 
propellers,  two  tractors  and  one  pusher. 

French  and  British  Bomb -Dropping 
Machines 

The  following  are  a  few  of  the  many  French 
and  British  bomb-dropping,  gun-carrying  ma- 
chines: 

The  British  Handley  Page,  equipped  with 
two   Rolls-Royce   motors.      This    biplane    has 


carried  21  passengers  in  one  flight  and  has  a 
top  wing-spread  of  98  ft.  and  a  lower  wing  of 
98  ft.     It  has  mountings  for  large  guns. 

The  twin-motored  Avro  biplane,  a  triplace 
equipped  with  various  kinds  of  motors. 

In  the  "short  distance"  class  of  bombers  are: 
The  Sopwith  130  h.p.  triplane  known  as  the 
"Tripe  Hound."  This  is  a  single  seater 
equipped  with  a  Clerget  motor. 

The  two  seater  1Y2  strut  Sopwith  biplane 
equipped  with  a  Clerget  motor.  This  is  used 
extensively  by  the  Royal  Naval  Air  Service  for 
bombing,  and  the  Royal  Flying  Corps  for 
fighting. 

To  these  must  be  added  the  machines  de- 
signed by  the  Royal  Aircraft  ISIanufactory, 
which  include  the  BE-2C,  R.  A.  F.  motor,  rather 


Caproni  biplane:  the  small  Italian  fifljhting  Monoplane,  and  the  Caproni  bombing  biplane. 


14 


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POSITION    OF    SIGHT 
when  bomhs  arc  rcleasi-d  on  lo 
2nd  Tari(ct 

The  l*f>in!cr  (sec  dUij(rani  inset) 
was  first  set  at  12  dc4rcc\  ;  then 
vktial  ray  aJvjnccd  to  2nd 
'1  .irSct  hy  tiltinjt  prisni,  the 
'.:i4i.-l  bcinit  held  in  sntht  by 
^:  .iiJually  reducing  anfilc  until 
lidt-^rtts  rtachcd,  when  pointer 
:iiiil  bi^nihs  arc  rcIcawJ 


Dmawixo  muM  THE  Ix>MtK>N   Okai*i(u    SiiowiNti   IIow  Tiir  (itmiA   AiMH   Its   Homiim 

Thr  art  of  arrlal  iMmibardmrnt  \h  liirjrrly  n  ?imttrr  of  lurk.  To  n'tliirr  this  i-Innrnt  thr  rnrmy  bus  pnKlutvd  the  instruinciit  lllus- 
tratrd,  thr  Grorz  boinlwIroppcr'H  trloM-opic  hijrht,  which  Is  included  In  the  equipment  of  the  Uotha,  wliich  lias  u  speed  of  ninct/- 
thrrc  miles  an  hour,  therefore  make«  accurate  hitting  dlfHcult. 


THE  WARPLANE  FOR  BOMBING     AND  TORPEDO  ATTACKS 


15 


British  airmen  taking  the  offensive  against  a  German  brigade  concentrating  for  .ittnck  near  Arras.  The  aviators  discovered 
the  Germans  concentrating  for  an  attack  and  dropped  heavy  bombs  on  them,  destroying  their  machine  guns  and  ammunition  and 
dispersing  them.  In  addition,  the  aviators  advised  the  British  artillery  which  opened  fire  on  the  German  concentration,  so  that  the 
German  attack  was  never  even  launched. —  (Drawing  by  the  "Illustrated  London  News'"  artist.) 


slow  and  a  poor  climber,  but  a  good  machine  for 
night  flying,  on  account  of  its  inherent  stabil- 
ity; the  BE-2E,  the  FE,  which  is  a  two-seater 
pusher  fighting  machine ;  which  is  a  faster  scout, 
just  being  tested,  and  the  BE-12.  Also  the  two- 
passenger  Avro,  armed  with  one  or  two  guns. 

The  French  also  use  a  great  many  different 
types  of  machines,  the  following  being  used  for 
bomb-dropping: 

The  Breguetj  equipped  with  a  single  motor. 

The  Caudron  G-4,  pilot  and  observer; 
equipped  with  two  La  Rhone  motors. 


The  Caudron  R-4,  three-passenger. 

The  Farman,  pusher  type,  two-passenger, 
equipped  with  one  Renault  motor. 

The  Germans  have  several  tj^pes  of  bombing 
machines,  of  which  the  Gotha  is  most  prom- 
inent. It  is  a  biplane  equipped  with  two  260 
h.p.  jVIercedes  motors,  carries  fourteen  bombs, 
and  is  armed  with  three  guns. 

The  Huge  Curtiss  Triplane 

The  huge   Curtiss  triplane  air-cruiser  built 

for  the  British  Government  is  a  good  possibility 

The  Caudron  G-6,  two-passenger;  equipped     as  a  long-distance  bomb  carrier,  for  aerial  oper- 

with  two  La  Rhone  motors.  ations  against  Germany.     For  such  a  purpose 

The  Dorand  A-R,  two-passenger;  equipped     the  boat-hull  can  be  eliminated,  and  its  weight- 

with  one  motor.  carrying    ability    increased    thereby.      Having 

The  Farman,  pusher   type,   two-passenger;     multiple  power-plants,  it  can  make  the  flight 

equipped  with  170  h.p.  Renault  motor,  carry-     from  an  Allied  base  to  Kiel  or  Berlin  or  Essen 


ing  one  or  two  Lewis  guns  forward. 

The  Letort,  equij^ped  with  two  motors. 

The  Moineau,  three-passenger;  one  motor, 
connected  to  drive  two  propellers. 

The  Voisin-Peugeot,  two-passenger ;  equipped 
with  a  Peugeot  motor. 


with  a  good  margin  of  flying  ability. 

The  big  Curtiss  triplane,  with  a  few  changes 
in  construction,  will  make  a  most  efficient  tor- 
pedoplane,  capable  of  carrying  a  magazine  of 
torpedoes. 

The  new  three-motored  Gallaudet  seaplane 


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The  Twin-Motored  Handlcv  Pajrc  Bomhinfr  Biplane.  A  Handley  Pape  has  flown  from  London  to  Asia  Minor,  with  stops,  and 
dropped  bombs  on  Constantinople.  It  carried  seven  men,  spare  motors  and  supplies.  Larger  Handley  Pages  can  fly  across  the 
Atlantic  and   bomb  the   German   bases   and   munition  plants. 


The  Krrnrh  Farmnn  mnrhinc  rquip|>r<l  with  a  Dietrich  motor,  used  cxtrniilvrly  for  Immbing. 


THE  WARPLANE  FOR  BOMBING  AND  TORPEDO  ATTACKS 


17 


also  comes  in  the  class  of  long-distance  raiding 
machines  and  is  suitable  for  either  bomb-drop- 
ping or  torpedo-launching.  A  number  of 
other  large  machines  are  under  contemplation 
or  are  being  designed  by  different  American 
manufacturers,  but  the  details  are  not  yet  avail- 
able. 

Long-Distance  Bombing  Raids  Not  New 

Long-distance  bombing  raids  are  by  no  means 
a  novelty,  but  they  have  always  been  conducted 
with  only  a  few  aeroplanes  of  limited  carrying 
capacity,  which  carried  only  a  few  hundred 
pounds  of  bombs  besides  the  fuel  needed  for  the 
journey. 

Among  the  historic  bombing  raids,  for  sev- 
eral reasons,  is  the  raid  on  Karlsruhe,  on  June 
15,  1915.  It  was  conducted  by  twenty-three 
twin-motored  Caudron  machines  in  charge  of 
Captain  de  Kerillis,  and  dropped  close  to  50 
large  bombs  on  Karlsruhe.  Three  of  the  ma- 
chines did  not  return ;  they  had  to  land  and  were 
captured,  but  the  damage  to  Karlsruhe  was 
serious. 


In  the  very  first  bombardment  of  Sofia,  on 
April  21,  1916,  a  single  aviator  started  from 
Salonica,  flew  to  Sofia,  dropped  four  bombs  and 
proclamations  announcing  the  capture  of  Trebi- 
zon,  and  returned  to  Salonica.  This  exploit 
was  repeated  by  single  aviators  from  time  to 
time;  then  on  September  15,  1916,  it  was  re- 
peated by  four  aviators  who  left  Salonica  at 
6:20  and  arrived  over  Sofia  at  8:40.  They 
dropped  their  bombs,  many  of  which  were  effec- 
tive, and  returned.  They  had  crossed  the  Bal- 
kan iSIountains  at  6000  feet  without  trouble  and 
had  accomplished  what  an  army  could  not  have 
done.  The  only  limitation  was  that  the  aero- 
planes were  too  few  in  number  to  win  a  decisive 
victory.  In  every  raid  in  the  Balkans  only  four 
or  five  aeroplanes  participated. 

Among  the  most  remarkable  long-distance 
bombing  raids  were  the  raids  on  Essen  and 
Munich  by  Captain  de  Beauchamp  and  Lieu- 
tenant Daucourt,  on  September  24  and  Novem- 
ber 18,  1916,  which  have  been  repeated  since  by 
other  aviators.  The  raid  on  Ludwigshafen,  ac- 
complished on  May  27,  1915,  in  which  18  aero- 
planes took  part,  also  involved  a  flight  of  about 


Plotting  a  Bombing  Raid. 


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|-  1^/  ) 


\^-^/T-  1 1 1,'   ffi — ^J?^^ 


K^-^ /     ^ 


■7 


KIEL 


Plan  of  Kiel  and  Kiel  Canal  from  Count  de  Beaufort's  hook, 
"Behind  the  German  Veil."  The  author  points  out  that  Kiel 
is  derived  from  the  Anglo-Saxon  "Kille,"  meaning  "a  safe  place 
for  ships."  The  torpedoplane  will  make  it  unsafe  for  ships  to 
be  there. 

400  miles.  It  was  conducted  successfully,  and 
only  one  aeroplane  was  forced  to  land  and  was 
captured.  Another  classic  flight  was  the  bomb- 
ing raid  on  the  Mauser  Works  at  Oberndorf,  on 
Octol)er  12,  1916,  in  which  a  French  bombing 
squadron  and  a  British  bombing  squadron  par- 
ticipated, escorted  by  the  Lafayette  Flying 
Corps  fighters.  These  are  only  a  few  of  scores 
of  such  raids.  In  all  the.se  raids  the  aviators 
had  to  fly  from  five  to  seven  hours  continuously 


under  most  trying  conditions,  having  to  protect 
themselves  with  insufficient  arms.  A  night  raid 
in  large,  well-armed  warplanes  would  be  easy 
in  comparison — and  much  safer. 

Long-Distance    Allied    Raids    into    Enemy 
Country  in  the  Western  Theater  of  War 

The  following  list  of  the  most  important 
French  and  British  raids  in  1916,  together  with 
twenty-five  important  Italian  raids,  compiled 
by  London  "Aeronautics,"  is  reproduced  here- 
with for  reference  purposes: 

March  20 — ^Fifty  British,  French,  and  Belgian  aeroplanes  attack 

Zeebrugge  and  Houltade. 
Mahch  25 — Naval  raid  on  airship  sheds  in  Schleswig-Holstein. 
April  3 — Reprisal  raid  by  31   Allied  aircraft  on  enemy  canton- 
ments of  Keyem,  Essen,  Terrest,  and  Houthulst. 
April  23 — Naval  air  raid  on  Mariakerke. 
Apkil  24 — Anglo-Belgian  raid  on  Mariakerke. 
June  21-22 — French  drop  18  bombs  on  Treves. 
June  32 — Nine  French  aeroplanes  bomb  Karlsruhe,  and  ten  bom- 
bard Miilheim  (Rhine)  as  a  reprisal  for  the  bombardment  of 

Bar-le-Duc  and  Luneville. 
July  13 — French  aeroplane  carries  out  night  raid  on  Mulheim  as  a 

reprisal  for  the  bombardment  of  Luneville. 
July  19-20 — French  aeroplanes  bombard  military  establishments 

of  Lorrach  (Baden). 
July  22 — Twelve  French  aeroplanes  bombard  the  military  estab- 
lishments of  Miilheim. 
July  30 — Naval  raid  in  conjunction  with  the  French  on  benzine 

stores  and  barracks  at  Miilheim  (.\lsace). 
August  2 — Naval  air  raid  on  St.  Denis  Westrem  and  Mierelbeke. 
August    8 — Fir-t    night    raid    by    Adjutants    Baron    and    Em- 

manuelli  on  powder  factory  at  Rottweil,  on  the  Neckar. 
August  9 — Naval  attack  on  airship  shed  at   Evi-re. 
August   18 — Naval   aeroplanes   bomb  enemy  ammunition  dumps 

at  Lichtervelde. 
August  25 — Naval  aeroplanes  attack  airship  sheds  near  Namur. 
Septe.mber  2 — Naval  aeroplanes  bomb  shipbuilding  yards  at  Ho- 

boken,  near  Antwerp. 
September  3 — Large  squadron  of  naval  machines  bombard  enemy 

aerodrome  at  Ghistelles. 
SEPTf:MBER  7 — Attack  on  enemy  aerodrome  at  St.  Denis  Westrem 

carried  out  by   naval  aeroplanes. 
September  9— Naval  aeroplanes  attack  Ghistelles  and  Handzaeme 

aerodromes  and  also  the  ammunition  dump  at  Lichtervelde. 
September   9-10 — Second    night    raid   by    Adjutants    Baron    -ind 

Emmanuelli   on   powder   factorj-   at    Rottweil. 
September    11—15 — French    squadrons   bombard   by   night   works 

at  Rombach  and  Dillingen. 
September    1.5 — Naval  aeroplanes   bombard  batteries  at  Ostend. 
SEPTt:MBER  17 — Further  naval  raid  on  St.  Denis  Westrem  aero- 
drome. 
Septejiber   22 — Enemy   aerodrome  at  St.    Denis  Westrem  again 

boml>ed  by  naval  aeroplanes. 
September    23 — .\djutant    Baron    bombards    by    night    military 

establishments   at   Ludwigshafen,   and   continuing  his   route, 

bombs   Mannheim. 
.September  2+ — Captain  de  Beauchnmp  and  Lieutenant  Oauoourt 

bomb  the  factories  of  Essen    (Westphalia). 
September  24-25 — French  bombarding  squadrons  effect  by  night 

an  attack  on  the  blast  furnaces  of  Dillingen   (Rhineland) 

and  .Saarlnuis. 
.September  27— Naval  raid  on  airship  shed.s  at  Ev^re.  Berchem 

St.    Agathe.   and    Ettcrbeik. 
October   5 — French   bombard   aviation   ground   at   Colmar    (.\1- 

sace). 


THE  WARPLANE  FOR  BOMBING  AND  TORPEDO  ATTACKS 


19 


Night  raid  by  French  aeroplanes  on  electric  searchlights  and 
buildings  at  Zeebrugge. 

October  9-10 — Adjutants  Baron  and  Chazard  bombard  by  night 
the  Bosch  magneto  factory  at  Stuttgart. 

October    10-11 — French    night    raid    on    Lorrach    establishment, 
Colmar  aviation  ground,  and  Mulheim  railway  station. 

October    13— Franco-British    squadron    of   40    aeroplanes    bom- 
bard  the   Mauser  works   at   Oberndorf. 

October    32 — French    aeroplanes    bombard    blast     furnaces    of 
Ilagondange. 

October  23— British   aeroplanes  carry  out  a   further  attack  on 
Hagondange. 

November   9 — French   aviator   bombs   railway   station   of  Ofen- 
burg. 

November  10 — Xaval  raid  on  Zeebrugge  Ostend. 

Seventeen  British  aeroplanes  bombard  the  steel  works  of 
Frocklingen  (northwest  of  Sarrebruck)  and  other  factories 
in  the  Sarr  region. 

November  10-11 — Further  night  attack  by  French  aeroplanes  on 
same   factories. 

November  12 — A  squadron  of  naval  aeroplanes  carry  out  an  at- 
tack  on   Ostend   harbor. 

November   15— Further  naval   attack   on  harbor  and  submarine 
shelters  at  Ostend  and  Zeebrugge. 

November  17 — Successful  raid  on  Ostend  and  Zeebrugge  by  naval 
aeroplanes. 
Captain  de  Beauchanip  bombs  Munich  as  a  reprisal   for  the 
bombardments  of  Amiens. 

November  22 — Xaval  aviators  drop  bombs  on  torpedo  craft  and 
seaplane  sheds  at  Zeel)rugge. 

November    23-24 — French    aviators    again    bombard    Volklingen 
blast    furnaces. 

November  24— British  naval  aeroplanes  bombard  the  blast  fur- 
naces  of   Dillingen. 

November   28 — Xaval   aeroplanes   carry   out   an   attack  on  Zee- 
brugge harbor. 

December  27— Thirteen  machines  of  the  R.X.A.S.  bombard  blast 
furnaces  at  Dillingen. 
French  dirigible  l)ombards  factories  at  Hagondange  and  iron- 
works at  X'eunkirchen. 

Septe.mber   26 — Russian    aviators   again   attack   German   air-sta- 
tion on  Lake  Angern. 

December  13 — Successful  Russian  air-raid  on  Tarnopol-Zloczow 
rallwav. 


Italian  Theater 

Januaby    14 — Italian    air    squadron    bombards    Aisovizza    aero- 
drome. 

Jaxuahy   IT^Italian   aviator   bombs   Austrian   headquarters   at 
Volano. 

February  12 — Austrian  seaplanes  raid  on   Ravenna. 

February  18 — Italian  machines  carry  out  reprisal  raid  on  Laibach. 

April  3 — Italian   aeroplanes   bomb    railway   at   Adelsberg. 

Apkil   17 — Franco-Italian   raid   on   Trieste. 

April  20 — Italian  air-raid  on  Trieste. 

May  3 — Italian  airship   falls  into   ,\ustrian  hands. 

May  7 — Italian  air-raid  over  the  Adige  Valley. 

Juxe  3 — ^Italian  squadrons  bomb  encampments  in  the  Astico  val- 
ley. 

June  12 — Italian  seaplanes  bomb  Trieste. 

June    16 — Italian   squadron   of   thirty-seven   machines  bomb  en- 
campments in  the  N'os  Valley. 

August   1 — Italian   squadrons   bombard   the  Whitehead  Torpedo 
and  Submarine  Works   at    Flume. 

August  2 — Italian  aviators  bomb  Durazzo. 

August   15 — Italian    X''leuport   chasers    bomb   Austrian   encamp- 
ments near  Gorizia. 

August  16 — Italian   aviators  bomb  railway  at   Relnenberg. 

August  25 — Italian   air-squadron   bombs   railway-station  at  San 
Cristoforo. 

September  13 — Italian  machines  bomb  Trieste. 

Septe.mber   15 — Italian  squadrons   bomb  Comignano. 

Septe.mber  17 — Italian    squadrons   bomb    station    at    Dottogliano 
and   Scoppo. 

October  31 — Italian   squadrons   successfully  bomb   Trieste   rail- 
way. 

X'ovember   1 — Italian   X^ieuport-Caproni   squadron  bombs  enemy 
camps  in  the  Vippacco  Valley. 

November  7 — Franco-Italian  aircraft  carry  out  raid  on  the  Istrian 
coast. 

Xovember    14-15 — Italian   aviators   attack    airsheds   at   Prosecco 
and  the  pier  at  Trieste. 

December  30 — Italian  raid  on  Volano  and   RIfemberga. 

December   3 — Italian    aviators    attack    Dottogliano   and    Scoppo 
railway  stations. 

Southeastern  Theater 

January  23— Thirty-two  French  aeroplanes  bomb  Ghevgeli  and 
Monastir. 


One  of  the  three  Sperry  bomb  sights. 
The  Sperrys,  after  gaining  world-wide 
fame  in  making  scientific  instruments  for 
ships,  undertook  to  solve  the  most  difficult 
problems  in  aerial  navigation  and  aerial 
warfare.  Having  begun  in  the  early  days 
of  aeronautics  they  were  able,  through 
their  long  experience  in  aeronautics,  and 
thorough  knowledge  of  the  problems,  to 
evolve  some  most  efficient   instruments. 


20 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Jakuasy  28 — Fourteen   French  aeroplanes   bomb   Bulgar  camp 

northwest  of  Lake  Doiran. 
May  ^4 — Allied  raid  on  Ghevgeli. 
July  3 — Allied  aeroplane  droi)s  bombs  on  Sofia. 
AuocsT  18 — Nineteen  Allied  aeroplanes  attack  Monastir. 
August  23 — Russian  seaplanes  bombard  Varna. 
August  ^5-31 — Naval  air  raids  behind  Kavala. 
August  ^8 — French  aviators  destroy  aviation  park  at  Mrzenci. 
August  -29 — English  aeroplanes  bomb  Drama. 
September  -2 — Raid  on  Constanza. 
September  9 — Rumanian  aviators  bomb  Rustchuk. 
September   13-2^ — Naval   seaplanes  bomb   Bulgarian  coasts. 
September   14 — French  aviators  bomb  Sofia. 
SEPTE.MBER  18 — English  aviators  drop  bombs  on  Prosenik. 
September  26 — The   R.N..\.S.  bomb  Angista. 
October   11 — French   aviators  bomb  Prilep. 
October   15 — R.N..\.S.  bomb  the  Buk  bridge. 
October   -23 — Naval  aeroplanes  bomb   Buk  and   Drama. 
October  26-2'i — English  aviators  reach   Bucharest. 
October   -29 — News   of   the   evacuation   of   Constanza  carried   to 

Odessa   by   seaplane. 
October  31 — Naval  aircraft  bomb  railway  bridge  at  Simsirli. 
No\'E.MBER  3 — English  aviators  bomb   Bursuk. 
No\'ember     11 — Naval     aircraft     bomb     Seres-Drama     railway. 

Bombs  dropped   on   Campulung. 
November    18 — British   squadrons   bombard    Karjani,   Pravishta, 

and  Senultos. 
Xo\-ember  22 — French  aeroplanes  bomb  enemy  encampments  in 

tlie  Topolchani   and  Prilep  regions. 
November   J3-J9 — Naval   squadrons   bomb    Bulgarian   coast. 
November  29 — British  naval  aeroplanes  effect  great  damage  at 

Gereviz. 
December   I — Russian  air  raid  near  Constanza. 
December   14 — Naval  air  squadron  bombs  Kuleli-Burgas  bridge, 

on  the  railway  to  Constantinople.     ' 

The  Levant 

February  20 — English  aviator  destroys  enemy's  power  station  at 

El   He.ssana. 
April   12 — English  bomb  Smyrna. 

April   14 — British   naval    aeroplanes   bomb   Constantinople. 
May  18 — English  machines  bombard  El  Arish. 
May  25 — The  R.F.C.  bomb  advanced  posts  in  Sinai  Desert. 
May  29 — English  drop  more  bombs  on  Smyrna. 


June    13— The    U.F.C.   bomb   El    Arish. 

August  25-29 — English  aviators  cany  out  many  raids  in  Pales- 
tine. 

September  4 — R.F.C.  bomb  Mazar. 

September  5 — English  aviators  bomb  Turkish  aerodrome  at  El 
Arish. 

October   1— English   bombs   dropped   on   Kut-el-Amara. 

Octobek    10 — U.F.C.    bombs    Tigris   camp. 

Novembeb  1 — Russian  aviators  carry  out  successful  raid  on  the 
Euphrates. 

Nove.mbeh  11 — English  aviators  carry  out  two  successful  raids 
on  Maghdaba  and  Birsaba. 

Xove.mber  15 — English  aviators  bomb  Turkish  base  near  Sinai. 

December  4 — English  aviators  carry  out  reprisal  on  Turkish 
camps. 

December  14-15 — British  aviators  attack  Tigris  pontoon  bridges 
by  night. 

Aeroplane  Raids  on  England,  1916 

Casualties 

Date                                District                                  Killed  Injured 

Jax.    23    East  Coast  of  Kent 1  6 

Feb.     20    East    and    Soutlieast    Coasts — Lowes- 
toft and  Walmer 3  "h 

■  Mae.     1     Southeast   Coast    1  — 

19  East  Kent — Dover  and  Ramsgate 9  31 

April  24     Dover     —  — 

May      3     Deal   ,. —  1 

20  East  Coast  of  Kent   1  2 

Aug.    12     Dover     — •  7 

Oct.     22     Sheerness    —  — 

23     Margate     —  3 

Total    15  59 

Nov.    28    London    —  9 


Extensive  Damage  Can  Be  Done  by  Bombs 

The  damage  that  can  be  done  by  bombs  is 
extensive,  particularly  in  thickly  settled  places. 
In  fast  raids,  whole  factories  and  magazines 


Incendiary  bombs 
dropped  on  English 
soli  by  Zeppelins,  some 
bum<-<l  out  and  some 
still   active. 


THE  WARPLANE  FOR  BOMBING  AND  TORPEDO  ATTACKS 


21 


The    French    Briguet 
Michelin  warplane, 

equipped  with  one  220 
horse-power  Peugeot 
motor.  This  machine  is 
used  extensively  for 
bombing. 


have  been  blown  up,  railroad  stations  wiped  out, 
bridges  wrecked,  hangars  and  dirigibles  de- 
stroyed, ships  destroyed  in  their  docks,  and  mili- 
tary camps  and  billets  destroyed. 

The  damage  has  been  considerable,  even  when 
only  a  few  aeroplanes  were  employed.  The 
emjiloyment  of  hundreds  of  aeroplanes  would 
■wreck  entire  militaiy  and  naval  bases.  A  fleet 
of  hundreds  of  torpedoplanes,  cooperating  with 
bomb-dropping  planes,  could  attack  the  Ger- 
man fleet  at  its  base  from  every  side,  as  well  as 
from  above,  and  inflict  tremendous  damage,  if 
not  destroy  it  completely.  It  depends  entirely 
upon  the  number  of  aeroplanes  employed,  and 
whereas  a  fleet  of  hundreds  of  torpedoplanes 
and  bombing  aeroplanes  would  cost  far  less  than 
a  naval  squadron,  and  could  be  built  and  oper- 
ated much  quicker — it  could  strike  at  the  Ger- 
man fleet,  whereas  a  naval  squadron  could  not 
— it  is  evident  that  aeronautics  affords  the  quick- 
est and  most  effective  way  to  strike  the  German 
fleet,  the  U-boat  bases,  and  the  German  military 
centers.  It  is  the  opinion  of  leading  strategists 
that  such  extensive  aerial  operations,  combined 
with  naval  operations,  could  reduce  the  most 
impregnable  naval  bases. 

Night  Facilitates  Bombing  at  Close  Range 

Night  facilitates  bombing  at  very  close  range. 
The  aviator  can  fly  close  to  his  target  and  hit  it 
in  the  most  vulnerable  points. 

The  first  part  of  aerial  attack  can  be  carried 


out  by  surprise,  and  half  of  the  work  is  done  be- 
fore the  searchlights  and  anti-aircraft  guns  are 
put  in  operation.  In  a  raid  of  hundreds  of  aero- 
planes the  searchlights  and  anti-aircraft  guns 
could  not  cope  with  the  situation.  Any  plan  to 
prepare  all  the  naval  and  militar\^  bases  so  as 
to  have  sufficient  anti-aircraft  defenses  to  cope 
with  the  situation  would  involve  employing  tens 
of  thousands  of  gunners  and  their  personnel, 
withdrawing  them  from  the  fronts,  and  thereby 
weakening  the  German  lines. 

If  the  night  should  happen  to  be  extremely 
dark,  the  aeroplanes  could  light  up  the  area  to 
be  bombarded  by  dropping  parachute  flares. 

Need    of    SilAic^^^to    Eliminate    Noise    of 
N.  ^)proach 

Silencers  are  needed  on  aeroplane  engines  to 
eliminate  the  noise  of  approach,  which  is  the 
only  thing  that  warns  the  enemy  of  the  ap- 
proaching warplanes  at  night.  The  silencers 
must  do  their  work  thoroughly,  eliminating  the 
exhaust  sounds  entirely,  because  the  anti-air- 
craft units  have  very  powerful  microphones  that 
magnify  the  slightest  sound. 

Lacking  silencers — for  no  reason  other  than 
the  added  weight  and  slight  loss  of  power — 
raiding  aeroplanes  are  forced  to  fly  at  high  alti- 
tudes in  an  attempt  to  escape  detection.  The 
weight  of  the  fuel  needed,  and  the  horse-power 
and  time  spent  in  evading  detection  in  this  way, 
represents  really  a  greater  loss  of  efficiency  than 
the  loss  caused  bv  the  silencers. 


k 


22 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


3iIoiuistir,  photographed  by  a  French  aviator  while  under  fire. 

Bombs  and  Bomb-Holding  Gears 

The  following  types  of  bombs  are  in  use:  16- 
poiind  bombs,  56-poiind,  and  100-  and  112- 
pound  bombs.  In  some  cases  there  are  bombs 
weighing  500  pounds  or  more. 

The  16-pound  bombs  are  usually  arranged  in 
series  of  four  under  the  fuselage.     The  releasing 
^ear  is  worked  from  a  bowden  wire  which  actu- 
.ates  a  bar  releasing  the  bombs  in  the  following 
order:     1,  4,  2,  3,  which  avoids  unequal  distribu- 
tion of  weight.     The  56-pound  bombs  are  usu- 
ally carried  in  a  series  of  two,  and  are  released 
in  the  same  fashion.     The  100-pound  and  112- 
pound  bombs  are  always  carried  in  single  bomb- 
frames.     These  have  two  levers,  one  to  fuse  the 
bomb  and   the  other   for   releasement.     These 
bomb-frames  are  usually  slung  on  either  side  of 
the  fuselage  Ik;1ow  the  lower  plane,  and  aft  of 
the  axle.     In  all  the  above  cases  the  bomb  is 
held  horizontally  in  a  fore-and-aft  position,  the 
nose  of  the  l)omb  pointing  forward. 

In  all  the  latest  types  of  machines  the  bombs 


are  carried  in  a  vertical  position  inside  the  body 
of  the  aeroplane,  nose  downward.  This  is  a 
ygj.y  great  saving  of  head  resistance.  For  ob- 
vious reasons  it  would  be  inadvisable  to  give  de- 
tails of  these  bomb-dropping  devices,  which  per- 
mit the  aviator  to  drop  one  or  all  of  the  bombs 
simultaneously. 

Dropping  bombs  weighing  500  pounds  or 
more  is  not  difficult ;  heretofore  it  has  been  more 
difficult  to  get  large  aeroplanes  capable  of  carry- 
ing them.  Now  that  large  warplanes  are  com- 
ing into  use  in  quantities,  the  dropping  of  bombs 
weighing  500  pounds  or  more  will  be  common, 
likewise  the  launching  of  torpedoes  weighing 
from  200  to  1500  pounds. 

Bomb-dropping  with  dirigibles  differs  little 
from  dropping  bombs  from  aeroplanes,  except- 
ing that  whereas  the  dirigible  makes  such  a  large 
target,  and  moves  much  slower  than  the  aero- 
plane, it  cannot  come  as  low  as  the  aeroplane  to 
drop  the  bombs.  On  the  other  hand  a  Zeppelin 
can  carry  three  or  more  tons  of  explosives  and 
can  remain  in  the  air  forty  hours  continuously. 

Zeppelin  Bomb-Dropping  Mechanism 

The  bomb-dropping  mechanism  of  a  Zeppelin 
captured  by  the  British  was  described  in  a  recent 
number  of  the  London  Sphere.  There  are  sixty 
bomb-droppers  for  conical  bombs.  The  base  is 
slung  in  straps,  and  there  is  a  strap  around  the 
neck.  The  latter  has  a  releasing  hook,  and  when 
the  releasing  hook  is  operated,  the  small  end  first 
drops  down  and  the  base  slides  out  of  its  straps. 
The  bomb  then  rights  itself  and  drops  base 
downward.  The  bombs  are  slung  in  one  or  two 
lines  along  the  under  side  of  the  hull.  The  re- 
leasing hook  is  operated  by  an  electro-magnet, 
and  there  is  a  small  switchboard  in  the  cabin  for 
controlling  the  release.  Each  bomb  has  a  sepa- 
rate switch.  The  bombs  can  be  released  by  hand 
levers  also,  in  case  the  electric  power  should  fail. 
Each  bomb  has  a  safety  device  and  is  not  "alive" 
until  it  has  dropped  several  hundred  feet. 

Bomb  Sights — The  Scientific  Side  of  Bomb- 
Dropping 

Bomb-dropping  from  heights  can  only  be  ap- 
proximately accurate.     It  can  be  made  more  ac- 


THE  WARPLANE  FOR  BOMBING  AND  TORPEDO  ATTACKS 


28 


GettinfT  ready  to  deliver  a  load  of  bombs  to  Gennanv.    Adjutant  Maneval,  of  tlu-  French  Air  Serxice,  has  painted  on  his  aeroplane 
the  following, '"General  Transport  Agency— Rapid  Service— Delivered  at  home!"      (Official  photo.) 


curate  by  the  employment   of  efficient  bomb 
sights. 

A  few  of  the  older  aviators  have  learned  by 
long  practice  to  drop  bombs  accurately  without 
sights,  but  as  a  general  rule  one  can  be  more 
accurate  with  the  sight  than  without  it.  There 
are  a  number  of  highly  ingenious  bomb  sights 
used  bv  aviators. 


Night-Bombing   Requires  Knowledge  of 
Aerial  Navigation  by  Instruments 

Night-bombing  requires  considerable  tech- 
nical knowledge  and  much  actual  experience  of 
aerial  navigation  if  it  is  to  be  effective.  It  is 
important  that  the  use  of  navigating  instru- 
ments be  familiar,  and  the  success  of  the  work 
depends  obviously  upon  accuracy. 


One  of  the  liundreds  of  munition  depots  wliich  must  be  piuli^eitJ  iiuui  ciitiny   bumbs. 


24 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Dropping  bombs  from  a  French  airship  at  night,  depicted  by  a 
French  artist. 


The  instruments  used  in  the  British  Naval 
Air  Service  for  night-bombing  are : 

Compass — Before  starting,  the  wind-force 
and  direction  are  taken.  Taking  into  consider- 
ation the  height  at  which  the  pilot  will  fly,  the 
course  is  plotted,  and  the  pilot  then  has  the 
course  which  he  will  steer  by  his  compass.  Also 
he  has  the  course  he  will  steer  coming  home. 

Air-Speed  Indicator,  or  Meter — This  is  es- 
sential because  the  pilot  will  throttle  down  his 
engine  in  order  to  spare  it,  and  it  is  essential  that 
he  should  know  his  speed,  so  that  he  can  calcu- 
late by  the  aid  of  his  cloth  at  what  time  he  may 
expect  to  be  over  his  objective. 

Spirit-Level,  or  Lateral  Inclinometer — This 
is  an  exceptionally  useful  little  instrument,  for 
as  long  as  the  bubble  remains  in  the  center  the 
pilot  knows  that  he  is  handling  his  controls  in 
the  correct  manner,  even  though  he  be  on  a  ver- 
tical bank. 

Inclinometer — This  instrument  gives  the  po- 
sition of  the  machine  fore-and-aft,  and  is  quite 
useful,  as  it  enables  the  pilot  to  determine  the 


angle  at  which  his  machine  is  either  diving  or 
climbing,  or  whether  he  is  flying  level. 

Altimeter — An  accurate  altimeter  is  impor- 
tant. This  will  indicate  to  the  pilot  the  height 
above  sea-level,  and  a  pilot  flying  at  night 
should  be  well  acquainted  with  the  height  above 
sea-level  of  all  surrounding  country,  particu- 
larly any  aerodrome  upon  which  he  may  be 
forced  to  land. 

Night  Landing-Lights 

In  England  during  the  early  days  of  Zeppe- 
lin raids,  the  casualties  resulting  to  pilots  who 
went  up  at  night  to  attack  Zeppelins  was  very 
high.  This  was  mainly  due  to  two  things: 
(l)  An  insufficient  number  of  badly  lighted 
night-landing  grounds;  (2)  Lack  of  lighting 
devices  on  the  machines. 

These  conditions  resulted  in  a  tremendous 
handicap  to  British  pilots.  Being  out  in  the  sky 
at  night  is  worse  than  being  out  in  a  small  boat 
at  night.  In  moonlight  one  can  pick  out  places, 
but  without  moonlight  flying  is  difficult.  The 
safest  way  is  to  use  a  double-motored  machine. 
Then  there  is  no  necessity  for  hasty  landing  if 
one  of  the  motors  develops  trouble.  Nor  must 
the  pilot  forget  the  recognition  signal  which  he 
must  flash  when  he  wants  to  land.  This  signal 
is  changed  each  day. 

In  addition  to  the  Verys  pistol,  night  flying- 
machines  are  specially  equipped  with  a  ])ara- 
chute  flare.  This  is  fired  electrically  from  the 
pilot's  seat,  through  a  tube.  On  release,  the 
electric  connection  is  made,  and  the  flare,  un- 
folding a  couple  of  hundred  feet,  explodes,  re- 
leasing a  small  silk  parachute  with  a  very  bright 
light  attached.  This  illuminates  the  country 
for  a  radius  of  approximately  a  quarter  of  a 
mile,  and  gives  the  pilot  a  chance  to  select  a  de- 
sirable landing-ground.  In  addition  to  this, 
there  are  attached  to  the  machine : 

(1 )  Holt's  Landing-Lights— These  are  flares 
attached  to  the  underside  of  the  wing-tips,  and 
ignited  electrically.  LTpon  connection  being 
made,  these  ignite,  throwing  a  very  strong  light 
downward.  This  is  reflected  downward  by  the 
wings,  and  so  does  not  dazzle  the  pilot,  and  if 
the  ground  is  practicable  for  landing,  he  may 
easily  make  a  perfectly  good  forced  landing. 


THE  WARPLANE  FOR  BOMBING  AND  TORPEDO  ATTACKS 


25 


(2)  Electric  Headlights — these  are  not  ar- 
ranged the  same  way  on  all  machines.  Some 
have  a  single  light  slung  just  underneath  the 
fuselage,  and  others  have  one  on  each  wing-tip. 
These  lamps  are  merely  very  powerful  automo- 
bile head-lamps,  very  well  streamlined,  so  that 
the  pilot  can  switch  them  on  or  off  at  will.  They 
are  used  in  a  similar  manner  to  Holt's  landing- 
lights.     (See  chapter  on  Night  Flying.) 

Navigation  Lights 

These  are  composed  of  one  light  in  the  tail 
and  one  on  each  wing-tip.  The  wing-tip  lights 
show  a  white  light  forward,  a  green  light  on  the 
starboard  side,  and  a  red  on  the  port  side.  The 
power  for  these  electric  lights  is  obtained  from  a 
small  dynamo  driven  by  a  miniature  propeller. 

There  is  one  small  disadvantage  in  the  use  of 
Holt's  landing- lights ;  that  is,  if  the  machine 
crashes  on  landing  before  the  lights  have  finished 
burning,  they  may  very  easily  set  fire  to  the 
whole  machine.  In  using  the  parachute  flare 
the  pilot  should  always  carry  a  short  stick,  about 
three  feet  long,  so  that  in  case  the  flare  jams  in 
the  tube,  for  many  reasons,  he  can  poke  it 
through  with  the  stick,  for  if  he  does  not,  there 
is  a  chance  of  the  flare  exploding  inboard  and 
setting  fire  to  the  whole  machine. 


The  Sperry  Automatic  Pilot 

The  work  of  the  night-bombing  squadrons 
can  be  made  much  easier  by  equipping  the 
bombing  machines  with  the  Sperry  automatic 
pilot.  How  this  remarkable  instrument  can 
help  is  told  by  Mr.  Lawrence  B.  Sperry,  as  fol- 
lows: 

"The  most  evident  advantages  that  the  Auto- 
matic Pilot  secures  in  bombarding  operations 
are  the  following: 

"The  facilitating  of  night-flying. 

"The  accuracy  and  simplification  of  bomb- 
dropping. 

"The  elimination  of  one  man. 

"The  reduction  of  physical  effort  on  the  part 
of  the  pilot. 

"Night-Flying.  The  bewilderment  that 
comes  on  a  dark  night,  due  to  the  pilot's  imper- 
fect sense  of  horizontality,  is  accentuated  to  a 
high  degree  when  he  is  unable  to  secure  those 
visual  impressions  that  he  is  wont  to  use  in  the 
daytime.  At  night  the  pilot  must  depend  for 
his  sense  of  horizontality — experts  tell  us — on 
the  reflex  actions  of  certain  semi-circular  canals 
located  in  the  interior  of  the  ears  and  tactile  im- 
pressions coming  from  the  nerves,  particularly 
those  in  the  soles  of  the  feet  and  other  support- 
ing portions  of  the  body.     It  is  not  generally 


^^^ 


Shaven  ^***Mamt?ung 

;;emer  haven 


^•^-^B! 


.«t' 


.IN 


SOME    OF  THE  RECORD 

NON-STOP  LONG  DIS- 

TANCE   FLIGHTS 


Lieut.  March*)  of  French  AmTi 
Jiue  20,  1916,  from  Nancy, 
over  Berlin  »  dwhn  Rnuia, 
807  mile*. 

Ruth  Law,  ChiaiD  >o  Hattiell, 
N.  Y.,  Nof.  19,  J916, 590  mlle» 
in  4  hr*.  17  min.  -30  sec 

Victor  Carlitronii  Chicago  to  Em, 
Pa.,  Nov.  2,  1S16,  452  milas. 
Newport  Newt  to  New  York, 
May  20,  1916,  400  miles. 

A.  Seguin,  duratioB  flight  _ 
France,  Oct  13^  1913,  648 
miles. 

R.  Boehm,  duration  flight  — 
Germany,  July  12,  1914,  re. 
mained  in  air  24  hrs.  12  min. 


Sketch-plan  showing  an  outline 
topographic  view  of  the  Allies  po- 
sitions in  relation  to  Heligoland, 
Kiel  and  Essen.  The  distance 
from  the  nearest  Allied  aeronautic 
centers  on  British  soil  to  Kiel  is 
only  about  275  miles.  There  are 
now  warplanes  which  are  capable 
of  carrying  over  one  ton  of  ex- 
plosives over  a  distance  of  seven 
hundred  miles  or  more,  and  there- 
fore capable  of  reaching  Kiel  at 
night.  One  thousand  warplanes 
dropping  a  ton  of  bombs  on  the 
German  fleet  and  U-boat  bases 
could  severely  damage  the  Ger- 
man fleet. 


26 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


A  huge  mountain  of  supplies  for  tlic  A..-li:  i";., -,  (_nriMi::\  hi-  ouniu'  niountain-  "i  Mi^ijiiie^  for  lirr  .-innic^  whirli  can 
be  destroyed  by  conducting  major  aerial  operations  against  the  German  bases,  thereby  seriously  impairing  the  efficiency  of  the  work 
of  the  German  forces. 


known  that  these  impressions  are  susceptihle  to 
serious  error,  due  to  centrifugal  force  or  acceler- 
ation pressures,  which  are  capable  of  reproduc- 
ing and  even  multiplying  gravitational  sensa- 
tions, when  the  machine  approaches  an  unaccus- 
tomed inclination.  The  misinterpretation  of 
these  sensations  has  often  resulted  disastrously. 

"Bomb-Dropjnng.  In  bomb-dropping  it  is 
quite  needless  for  us  to  discuss  the  absolute  ne- 
cessity of  having  a  gjToscopic  horizontal  refer- 
ence plane  of  integrity  and  accuracy,  or  to  enu- 
merate the  inaccuracies  to  which  pendulums, 
mercury  tubes,  and  other  gravity  devices  are 
susceptible.  Our  experts  have  long  ago  ex- 
posed the  total  unreliability  of  all  of  these  de- 
vices. 

"The  gjToscopic  apparatus  is  capable  of  stay- 
ing within  one-quarter  of  one  degree  to  the  true 
horizontal.  A  sensitive  aeroplane  is  held, 
through  the  intermediary  of  the  servo  motor  and 
follow-up  system,  within  three  quarters  of  one 
degree  of  the  position  of  this  gj'roscopic  plane. 
This  variation  of  three  quarters  of  a  degree 
might  seem  to  the  layman  to  be,  in  eflFect,  a  cor- 
responding inaccuracy,  but  any  one  accustomed 
to  reading  a  baragraph,  the  index  of  which  is 
designed  to  tremb'e  or  vibrate  constantly,  will 
appreciate  the  eas'j  and  accuracy  with  which  the 
pilot  bomb-dropper  can  secure  his  objective  in 
the  mean  of  two  extreme  positions,  especially 
when  close  to  each  other.     In  this  way  more  ac- 


curate results  can  be  obtained  than  with  non- 
oscillating  conditions,  because  this  motion  makes 
all  the  parts  of  the  follow-up  mechanism  ex- 
tremely sensitive,  as  in  the  case  of  the  baragraph. 
Furthermore,  the  slight  motion  assures  the  op- 
erator that  the  apparatus  is  functioning  prop- 
erly, while  he  need  only  consult  his  clinometer, 
located  on  the  g>'ro  unit,  to  check  up  accuracies. 

"The  proposition  to  connect  the  bomb  sight 
directly  to  the  gj^roscopic  element  involves  ham- 
pering its  freedom  by  friction  of  the  connection 
links,  and  by  the  inertia  vibrations  of  the  sight; 
in  addition,  pressure  of  the  hand  in  making  ad- 
justments is  likely  to  cause  inaccuracies.  It 
is  always  advisable  to  leave  the  gyro  as  free  and 
unmolested  from  outside  forces  as  possible. 

"With  the  bomb  sight  rigidly  fixed  to  the  side 
of  the  machine  or  to  the  floor,  the  method  of 
sighting  is  somewhat  as  follows: 

"With  the  gyro  manual-control  the  position  of 
the  aeroplane  is  adjusted  until  both  clinometers 
read  zero.  The  operator  then  seciu-es  by  his 
rudder  the  motion  of  some  objective  in  his  field 
of  vision,  parallel  to  the  longitudinal  cross-wire. 
During  this  time  the  deviation  angle  is  set  by 
taking  the  usual  stop-watch  reading,  or  by  other 
steps  involving  this  very  simple  oijcration.  The 
pilot  bomb-dro])per  has  now  only  to  keep  his 
ultimate  objective  moving  along  the  longitudi- 
nal wire,  before  releasing  the  bomb  when  it 
reaches  and  crosses  the  lateral  wire. 


THE  WARPLANE  FOR  BOMBING  AND  TORPEDO  ATTACKS 


27, 


i'  "The  increased  accuracy  of  bomb-dropping 
from  an  aeroplane  equipped  with  the  Automatic 
Pilot  is  due  to: 

"1.  Being  able  to  get  the  aeroplane  more  ac- 
curately lateral  over  the  target. 

"2.  Being  able  to  release  the  bomb  at  the 
proper  angular  distance  from  the  target. 

"3.  Simplifying  the  operation  of  bomb-sight- 
ing, since  the  sight  is  held  automatically  and  ab- 
solutely horizontal,  the  reby  allowing  the  pilot 
bomb-dropper  to  focus  his  entire  attention  on 
adjusting  the  sight  and  steering  the  aeroplane. 

"During  the  long  night  bombardments,  the 
elimination  of  the  extra  passenger  has  the  ad- 
vantage of  either  increasing  the  radius  of  action 
or  of  enlarging  the  bomb-carrying  capacity  of 
the  machine;  while,  of  course,  in  the  event  of 
failure,  one  man  is  lost  instead  of  two.  The 
physical  work  of  which  the  pilot  is  entirely  re- 
lieved in  long  bombardment  trips,   especially 


with  the  larger  types  of  aeroplanes,  would  fre- 
quently be  too  much  for  the  ordinary  pilot." 

Turn  into  the  Wind  to  Avoid  Drift 

In  bombing-raids  drift  is  one  of  the  most  dif- 
ficult factors  to  conquer  by  the  use  of  instru- 
ments, because  of  the  difficulty  of  calculating 
with  accuracy,  especially  at  night.  There  is  a 
simple  solution  to  this  problem,  however,  which 
is  always  to  turn  into  the  wind  when  about  to 
drop  the  bombs,  and  thus  avoid  the  drift  en- 
tirely. 

Formation  for  Bombing  Raids 

Suppose  one  thousand  large  bombing  ma- 
chines were  sent  to  bomb  Kiel,  Essen,  or  any 
other  important  German  base.  They  would 
probably  set  out  from  five  to  ten  aeronautic 


An  official  air-photopraph  of  Ostend  after  the  Rritisli  naval  bombardment.  It  will  be  seen  that  the  bombardment  was  directed 
against  the  Germans'  submarine  lair,  the  letters  indicatinft  the  principal  hits.  Thus  B  represents  the  damaged  entrance  pates  to 
basin;  C,  Q  and  R,  destroyers  struck;  D,  U  and  Z,  pier  and  jetties  hit.  The  other  letters  indicate  damage  to  the  submarine  har- 
bor and  adjacent  buildings.     Ostend   is  an  important  German   naval  base. 


28 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


bases,  on  carefully  drawn  plans.  As  there 
would  be  no  advantage  in  having  all  the  ma- 
chines arrive  at  the  same  time,  since  there  would 
be  possibility  of  confusion  and  crowding,  the 
plan  would  probably  be  to  divide  the  thousand 
aeroplanes  into  from  six  to  ten  wings,  each  wing 
to  consist  of  a  given  number  of  squadrons  in 
charge  of  a  squadron  commander. 

The  raid  would  have  to  be  carried  out  in  the 
darkness  between  sundown  and  sunrise.  In  the 
autumn,  winter,  and  spring,  when  the  nights  are 
longer,  such  raids  can  be  conducted  entirely  un- 
der cover  of  darkness,  and  the  raiders  have  little 
to  fear  from  anti-aircraft  guns  and  enemy  air- 
craft. In  the  first  large  night-raid,  made  in 
August,  1917,  by  232  Italian  aeroplanes,  only 
one  machine  was  lost,  the  others  being  protected 
by  darkness. 

In  a  raid  of  a  thousand  aeroplanes,  the  best 
effect  can  be  obtained  by  sending  units  of  200 
to  follow  each  other  at  intervals  of  half  an 
hour.  The  second  imit  arrives  after  the  first 
unit  has  done  its  work,  and  finds  the  theater  of 
war  ablaze  with  the  fires  started  by  the  first 
unit.  ^  The  lights  assist  in  picking  out  the  im- 
portant points  and  objects  to  be  bombed.    The 


succeeding  units  find  their  work  correspond- 
ingly easy. 

Rules  for  Formation  Flying 

The  rules  for  formation  in  this  case  would  be 
the  same  as  prescribed  by  the  General  Stafi"  of 
different  countries.  These  are  practically  uni- 
form, since  each  country  adopts  improvements 
as  fast  as  they  become  known,  which  happens 
whenever  a  squadron  or  flight  commander  is 
brought  down  and  printed  or  written  instruc- 
tions are  found  on  his  person. 

The  instructions  of  the  British  General  Staff 
to  squadron  and  flight  commanders  of  bombing 
units — which  are  also  applicable  to  fighting, 
reconnoitering,  photographing,  and  other 
branches  of  the  air  service,  are  as  follows: 

A  leader  must  be  appointed,  and  a  sub- 
leader,  in  case  the  leader  has  to  leave  the  forma- 
tion for  any  reason;  i.e.,  engine  trouble. 

The  leader  cannot  efficientlj^  control  more 
than  a  certain  number  of  machines.  If,  there- 
fore, this  number  is  exceeded,  the  mission  must 
be  carried  out  by  two  formations  acting  in  con- 
cert, but  each  with  its  own  leader. 


A  French  BrcKUct  tractor  binlune  used  fur  buiiibing,  photographing  and  artillery  spotting. 


THE  WARPLANE  FOR  BOMBING  AND  TORPEDO  ATTACKS  29 


Drawn  by  Frank  ilerritt  Courtesy  of  Motor  Boating 

Reducing  the  German  fleet  at  Kiel  with  present  day  warplanes. 


30 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


How   1000  Warplanes  Could  Raid  Kiel 

Suppose  1000  warplanes  were  to  start  from 
the  Allies'  lines  in  a  major  operation  against 
German  bases.  They  would  start  from  differ- 
ent aerotlromes,  probably  about  one  hundred 
from  each  aerodrome,  the  machines  following 
each  other  at  intervals  of  30  seconds. 

Squadrons  of  2.5  machines  would  probably  be 
fonned,  with  a  flight  commander  to  each  squad- 
ron, who  would  start  first.  The  aviators  of  each 
squadron  would  follow  as  fast  as  possible,  each 
aviator  following  the  navigation  lights  of  his 
s(juadron  commander.  A  prearranged  signal 
from  the  aerodrome  woidd  tell  the  squadron 
commander  when  the  last  machine  of  his  squad- 
ron left  the  ground,  and  he  would  then,  after  a 
brief  delay  to  give  time  for  the  machines  to 
climb  up,  give  the  signal  to  fall  in  line,  and  the 
squadron  would  travel  on  in  V  formation. 
Every  aviator,  of  course,  would  have  studied 
the  specially  prepared  chart  and  would  be  fa- 
miliar with  the  route — as  it  looks  to  the  aviator 
from  the  air. 

Thus  they  would  travel  the  450  or  so  miles 
between  the  Allied  bases  and  the  German  naval 
bases,  or  about  the  same  to  the  important  Ger- 


man militarj^  bases.  There  being  a  crew  of 
three  men  to  each  warplane,  the  aviators  would 
not  be  as  lonesome  as  they  often  are  in  bombing 
raids  alone. 

The  distance  woidd  be  covered  in  five  to 
six  hours.  And  then?  Then,  with  the  tor- 
pedoplanes  attacking  the  German  ships  from 
the  sides  and  the  bombs  attacking  from  above, 
the  hardest  blow  yet  struck  at  Germany,  the 
most  effective  blow  in  the  fight  for  humanity's 
rights,  would  be  struck! 

Just  as  the  battles  of  Manila,  Santiago,  and 
Tshushima  lasted  only  about  an  hour,  so  the 
battle  of  Kiel  would  be  over  in  one  hour,  because 
the  destruction  of  the  German  fleet  from  the  air 
would  make  it  possible  for  the  Allies'  mine- 
sweepers to  clear  away  the  German  mines  and 
open  the  way  for  the  Allies'  ships  to  deal  with 
U-boats  in  their  bases  at  close  range.  And 
Germany's  naval  power  would  be  crippled 
thereby — and  its  total  destruction  would  follow, 
through  repeated  raids  on  the  less  important 
U-boat  bases. 

So  let  us  not  lose  a  minute ;  let  us  concentrate 
the  nation's  efforts  on  turning  out  the  thousands 
of  torpedoplanes  and  warplanes  needed. 


Five  different  sizes  of  bombs  dropped  from  aeroplanes.    The  weight  of  aeroplane  bombs  to-day  varies  Irom  Hi  to  oOO  pounds. 


CHAPTER  III 

DROPPING  BOMBS  FROM  AEROPLANES 

By  Jean- Abel  Lefrance 


Last  February  a  French  aviator,  Captain 
Guynemer,  succeeded  in  bringing  down  inside 
the  French  lines,  one  of  a  raiding  squad  of  20 
German  bombarding  planes  of  the  newest  type, 
manufactured  by  the  Gotha  Wagonen  Fabrik. 
A  peculiarly  interesting  feature  of  the  aeroplane 
was  its  Goerz  sighting  telescope  or  range-finder, 
designed  to  facilitate  the  taking  of  correct  aim 
at  objects  to  be  bombarded.  A  careful  study 
of  this,  with  a  discussion  of  the  laws  governing 
the  dropping  of  bombs,  appears  in  "La  Nature" 


(Paris),  together  with  the  accompanying  dia- 
grams. 

Any  projectile  dropped  from  a  height  is  sub- 
ject, of  course,  to  two  constant  forces,  the  re- 
sistance of  the  air  and  the  acceleration  due  to 
gravity.  Its  trajectory  is  a  vertical  line  from 
the  point  of  discharge.  A,  to  the  striking  point, 
B  (Fig.  l) .  If  the  bomb  be  dropped  from  an 
airship  in  motion,  it  will  have  an  initial  speed 
equal  to  and  in  the  same  direction  as  that  of 
the  latter.     This  new  force  is  compounded  with 


31 


32 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Inae.x  and  bti5e  6 


Index  I 


CrortoaraY>h 


Uo.versol    j-^tnt 


Eut-pieccfJt— ■ 


Chronograph 


Controlling 
Disk  for  Prism 


Rodcontrollinq 
PrI.rr.      ^ 


Fig.  1.  Trejectorj'  of  a  bomb  falling 
from  an  aeroplane  as  affected  by  the  di- 
rection of  the  wind. 


Fig.  -2.    The  Goerz  range-finder. 


Fig.  3.    Diagram  showing  construction  of 
the  Goerz  range-finder. 


the  two  former,  and  the  result  is  the  curved 
trajectory'  A  C. 

If  this  bomb,  having  a  given  initial  velocity, 
is  dropped  into  a  layer  of  air  in  motion,  that 
is,  into  the  wind,  it  is  acted  on  by  the  latter, 
and  is  said  to  undergo  "drift."  If  the  wind 
is  at  the  back,  the  trajectory  is  lengthened,  as 
in  A  D;  if  there  is  a  head  wind,  the  trajectory 
will  be  shortened,  as  in  A  E. 

If  the  bomb  be  dropped  from  an  avion  which 
the  strength  of  the  wind  causes  to  be  stationary' 
with  respect  to  the  ground,  i.e.,  when  the  ve- 
locity of  the  wind  is  exactly  equal  to  that  of 
the  avion  and  in  the  opposite  direction,  the 
projectile  will  have  no  initial  velocity  and  the 


curve  of  its  trajectory  will  be  a  function  solely 
of  the  drift  produced  by  the  wind,  as  in  A  b; 
it  will  therefore  fall  to  the  rear  of  the  point  of 
departure.  This  latter  case,  however,  is  ex- 
ceedingly rare,  since  it  presupposes  a  wind  of 
120  to  1.50  kilometers  per  hour;  but  this  is  a 
gale  too  high  to  permit  the  sending  up  of  avia- 
tors. 

These  trajectories  being  given,  the  angle  of 
aiming  will  be  the  angle  formed  by  the  vertical 
line  A  V  at  the  point  of  departure  A  with  the 
straight  line  joining  this  point  A  with  the  strik- 
ing point  O,  i.e.,  the  angle  VAO. 

Since  these  trajectories  are  curves,  the  height 
of  the  avion  above  the  object  aimed  at  is  an 
element  which  modifies  the  value  of  the  trajec- 
tory. Since  the  wind  causes  drift,  this  drift  will 
vary  with  the  form  of  the  projectile  and  with 
the  velocity  of  the  fall.  Here  we  have  two  ele- 
ments which  are  constant  for  each  type  of  bomb. 

To  sum  up,  the  trajectory  of  a  bomb  dis- 
charged from  an  avion  is  the  resultant  of  the 
following  forces: 

Weight 


Form 
Drift 
Speed  of  avion  in 
wind 


Elements  constant  for  a  given  type  of 
bomb 


Considered  as  a  constant  for 
a  given  type  of  avion 


A  Vobin  bombing  machine  u^cU  bj   Uic  llusslunii  and  Uic  French. 


Other  Elements 
Height  of  shot 
Initial  speed  of  bomb,  i.e.,  of  avion 

with  respect  to  ground 
Velocity  of  head  wind 


Variable 
elements 


DROPPING  BOMBS  FROM  AEROPLANES 


88 


Of  these  three  principal  variable  elements 
which  it  is  necessary  to  know  for  each  case  of 
bombardment,  one  of  them,  the  velocity  of  the 
head  wind,  can  be  immediately  deduced  when 
the  velocity  of  the  avion  with  reference  to  the 
earth  is  known,  since  this  velocity  of  the  wind 
is  the  difference  between  the  velocity  of  the 
avion  with  respect  to  the  earth  and  its  normal 
velocity  in  the  wind,  an  element  which  is  fixed 
for  a  given  type  of  avion. 

Take  an  avion  having  a  normal  speed  of  150 
km.  per  hour;  if  it  is  only  going  100  km.  per 
hour  with  reference  to  the  earth,  then  it  is  fly- 
ing against  a  head  wind  of  50  km.  per  hour. 
Hence  it  is  only  necessary  to  know  the  height 
of  the  avion  and  the  initial  speed  of  the  bomb 
to  determine  a  trajectory.     This  method  of  cal- 
culating trajectories   seeks   to   base   itself   on 
science  in  order  to  obtain  a  mathematical  pre- 
cision in  its  results.     Unfortunately  it  is  based 
upon  a  probable  knowledge  of  atmospheric  con- 
ditions, which  are  essentially  capricious.     Par- 
ticularly, the  speed  of  the  wind  at  the  height  of 
the  avion  is  taken  into  account,  e.g.,  at  4000 
meters,  but  it  is  supposed  that  this  remains 
unmodified  down  to  the  ground,  which  is  rarely 
the  case  in  reality.     It  may  also  be  that,  starting 
from  3000  meters,  the  wind  changes  its  direction 
so  much  that  the  best  calculations,  the  best  tele- 
scopes, and  the  best  bombardiers,  are  unable  to 
secure  a  correct  aim,  so  that  some  authorities 
despair  of  ever  being  able  to  get  results  in  aerial 
bombardment  comparable  to  the  efforts  made. 
Goerz  Range-Finder. — This  is  certainly  the 
test  and  most  highly  perfected  effort  of  German 
science  to  find  means  of  destroying  railroads, 
factories,  and  populations  outside  the  range. of 
their  big  guns.     It  consists  of  a  telescope  about 
■one  meter  long;  mounted  on  a  universal  joint,  it 
can  be  oriented  in  every  direction  and  kept 
strictly  vertical  whatever  be  the  position  of  the 
•avion   (Fig.  2).     The  accompanying  diagram 
(Fig.  3)  shows  the  ensemble  of  the  optical  sys- 
tem; the  field  obtained  is  500/1000  and  the  en- 
largement is  1.5. 

At  the  base  of  this  telescope  is  a  prism 
mounted  on  a  pivot  and  controlled  by  a  grad- 
uated disk.  The  telescope  remaining  vertical, 
the  play  of  the  prism  permits  the  visual  ray  to 


Direct  to*^  o^  ^ovKmcrtt  of  Airopfortc^^ 


Figs.  4,  5,  6.     Direction  of  aim  in  the  finder. 

be  inclined  a  number  of  degrees  corresponding 
to  the  graduations  of  the  disk. 

On  this  disk  are  two  indexes,  one  correspond- 
ing to  the  vertical  speed,  or  dead  point  of  the 
range-finder,  and  the  other  to  the  vision  of  22° 
30'.  Another  index  serves  as  a  basis ;  it  is  fixed 
on  the  body  of  the  range-finder.  At  0°  the 
marksman  sees  the  ground  along  the  vertical 
(Fig.  4) ;  at  20°  the  inclination  of  the  visual 
ray  is  20°  in  front  of  the  avion  (Fig.  5)  ;  at  5° 
the  inclination  is  5°  behind  the  avion  (Fig.  6). 
A  small  index  is  movable  upon  the  disk,  but 
this  can  be  made  solid  with  it  bv  means  of  a  little 


Three  different  types  of  bombs  dropped  by  Allied  aviators  at 
Salonica. 


34 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


I   Ignilion 

Device 


Thermtt 


Reiinoui 
matter 


MclUo 

nkite 
piosphonm 


Section  of  Incendiarj-  Bomb  dropped  from  Zeppelins.  The 
Incendiarj-  bomb  illustrated  herewith  is  being  used  by  German 
airships  for  the  purpose  of  setting  afire  enemy  towns  and  mili- 
tarj'  establishments;  it  is  described  in  a  poster  published  by 
the  British  Fire  Prevention  Committee  as  follows:  "The  usual 
fire-bomb  dropped  by  a  Zeppelin  is  of  conical  shape,  the  diam- 
eter at  the  base  being  about  ten  inches.  It  is  wrapped  round 
with  inflammable  cord,  which  gives  it  rather  a  nautical  appear- 
ance, enhanced  by  a  handle  at  the  apex  for  lowering  it  over  the 
gunwale  of  the  airship — if  airships  have  gunwales.  The  base 
is  a  flat  cup,  and  from  this  to  the  handle  runs  a  hollow  metal 
funnel  forming  the  center  and  business  part  of  the  bomb.  This 
center  funnel  is  filled  with  thermite.  Thermite  is  the  prepara- 
tion which  on  ignition  produces  a  heat  so  intense  as  to  melt  steel. 
The  ignition  of  thermite  creates  a  tremendous  glare  of  light, 
and  the  heat  melts  the  metal  funnel.  The  molten  metal  spreads 
when  the  bomb  strikes.  It  sets  up  at  once  a  fierce  fire  if  it 
strikes  anything  combustible,  but  at  the  beginning  it  is  only  a 
small  fire,  and  if  it  is  tackled  at  once  with  water  it  can  be  put 
out  before  it  does  any  damage  to  speak  of. 


detent.  This  index  once  fixed  before  a  gradu- 
ation of  the  disk,  after  passing  the  dead  point 
falls  into  a  small  notch,  and  thus  informs  the 
gunner  that  he  sees  the  ground  according  to  the 
inclination  which  he  had  marked  with  this  index ; 
this  is  disengaged  by  a  slightly  stronger  pres- 
sure of  the  hand. 

In  the  body  of  the  telescope  is  a  spirit-level. 
The  edges  of  the  air-bubble  are  refracted  in  such 
manner  that  they  ap})ear  in  the  form  of  a  black 
circle,  which  sen'es  as  a  sighting  center  for  the 
telescope.  In  the  course  of  all  his  range-finding 
operations  the  gunner  must  keep  this  bubble  in 
the  center  of  the  ocular,  which  will  keep  the 


range-finder  vertical  no  matter  what  the  inclina- 
tion of  the  avion. 

The  universal  joint  permits  the  finder  to  in- 
cline freely  from  right  to  left  or  from  front  to 
rear,  but  when  it  revolves  around  its  vertical 
axis,  i.e.,  when  the  visual  ray,  instead  of  being 
directed  in  front  of  oi-  behind  the  avion,  is  di- 
rected to  the  right  or  the  left  of  the  route  fol- 
lowed, the  finder  acts  upon  a  route  corrector. 
This  consists  of  an  electric  device.  Resistances 
act  upon  a  very  sensitive  galvanometer  placed  in 
front  of  the  pilot  and  indicate  to  him  how  to  cor- 
rect his  route  in  order  to  make  it  pass  exactly 
above  the  object  to  be  bombarded. 

Method. — There  are  only  a  few  of  the  ele- 
ments constituting  a  trajectory  which  can  differ 
in  the  course  of  each  bombardment:  the  height 
of  the  avion  above  the  object,  the  initial  velocity 
of  the  bomb,  the  speed  of  the  wind.  The  Ger- 
man method  of  the  Goerz  finder  enables  a  calcu- 
lation of  these  three  elements  to  be  made. 

1.  The  height  is  obtained  by  subtracting  from 
the  altitude  range  shown  on  the  altimeter  of  the 
avion  the  altitude  of  the  object  bombarded;  e.g., 
if  the  avion  is  flying  at  4200  meters  above  sea- 
level,  and  if  the  factory  to  be  bombarded  is  200 
meters,  then  the  height  to  be  reckoned  with  will 
be  4200— 200— 400€  meters. 

This  method,  moreover,  is  subject  merely  to 


ii  ivu  iu  a 


stuck  of  Imy  on  EiigliUi  wil. 


DROPPING  BOMBS  FROM  AEROPLANES 


85 


very  slight  errors  where  high  altitudes  are  in 
question.  Example:  At  90  km.  an  error  of 
altitude  of  500  meters  for  an  avion  at  4000 
meters,  corresponds  to  an  error  of  only  25 
meters  at  the  ground  level  (Fig.  7) . 

2.  Initial  Velocity  of  the  Bomb. — In  reality 
this  is  the  speed  of  the  bomb  with  reference  to 
the  ground.  This  element  is  the  most  difficult 
to  know,  because  it  varies  with  the  velocitj^  of 
the  wind,  which  is  in  a  state  of  perpetual  insta- 
bility. If  an  avion  possesses  a  speed  of  150  km. 
and  the  wind  is  blowing  at  the  rate  of  50  km., 
then  with  a  following  wind  the  avion  will  travel 
at  200  km.  per  hour,  while  with  a  head  wind  it 
will  go  only  100,  This  difference  of  speed  con- 
siderably modifies  the  trajectories,  as  can  readily 
be  seen  by  examining  the  curves  in  Fig.  7,  in 
which  the  avion  is  going  120  and  60  km.  per 
hour  respectively.  In  place  of  being  simply 
added  or  subtracted,  this  speed  of  the  wind  and 
speed  of  the  avion  may  be  compounded  if  the 
avion  receives  the  wind,  for  example,  three  quar- 
ters to  the  rear  (175  km.  per  hour)  or  three 
quarters  head  on  (125  km.  per  hour) . 

In  principle,  to  simplify  the  calculations,  the 
avion  should  bombard  with  the  wind  head  on, 
i.e.,  with  the  speed  as  much  reduced  as  possible. 
To  determine  this  kilometric  speed  of  the  avion 
we  calculate  the  time  required  by  a  fixed  point 
on  the  groimd  O  to  traverse  an  angle  fixed  at 
45°  or  22°  30'. 

It  is  easy  to  see  by  the  figure  that  the  time 
required  by  an  avion  to  find  the  range  of  the  the  initial  horizontal  speed  of  the  bomb 
same  point  successively,  first 
with  an  angle  of  22°  50'  and  then 
vertically,  is  proportional  to  the 
speed  of  the  avion  with  respect 
to  the  earth.  A  value  in  sec- 
onds is  obtained. 

A  previous  prepared  table 
will  indicate  that  if  the  avion  be- 
ing at  an  altitude  of  4000  meters, 
a  point  on  the  ground  takes  36 
seconds  to  pass  through  an  an- 
gle of  22°  30',  then  the  avion  is 
going  100  km.  per  hour,  with 
reference  to  the  earth;  if  the 
point  takes  only  18  seconds  to 

pass  through  the  same  angle,  the  A  bomb  liropped  from  a  Zeppelin, 


Another  Speriy  bomb  sight  which  practically  does  all 
thinking  necessary  for  accurate  bomb-dropping. 


avion  is  going  200  km.  per  hour.     This  value  is 


36 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


0 

woo 

'^iOOO 

100     300jMtociM$eonetMt«c    loaei 

\ 

^ 

\ 

X 

\ 

< 

•A 
I  o 

1  ' 

\  V 

\ 

K 

3 

C 

3000 

< 

t 

1 

\ 

\ 

\ 

mo 

\ 

i 

c 

too      300     300     4O0      SOO     600      700      800      900     fOOO 
Oev.alion  m  Meters 

Fig.  7.    The  falling  curves  of  bombs  at  different  speeds. 


D-recliOrt  Control 
Gurtoe>-'»  seot 


Fig.  8.    Location  of  the  finder  upon  an  aeroplane. 

3.  Moreover,  it  is  known  that  avions  of  the 
Gotha  type  have  150  km.  per  hour  speed  when 
the  motors  are  revolving  at  their  usual  velocity ; 
if  the  preceding  range-finding  shows  the  speed 
at  the  ground  to  be  only  100  km.  per  hour,  the 
obvious  deduction  is  that  the  head  wind  has  a 
value  of  50  km. 

Thus  all  the  elements  of  the  trajectory  sought 
are  known ;  it  remains  only  to  read  on  the  chart 
which  firing  angle  is  suitable  to  cause  the  Iximb 
to  fall  on  the  given  object,  in  view  of  the  given 
elements. 

Several  minutes  before  arriving  over  the  ob- 
ject to  be  bombarded  it  is  necessary  to  ac(}uire  a 
knowledge  of  two  elements  which  will  enable 
the  gunner  to  read  on  the  chart  the  proper 
firing  angle.     The  altitude  range  on  the  ba- 


Fijr.  9.     Device  for  releasing  bombs. 

rometer  less  the  altitude  of  the  object  gives  the 
height  of  the  fall  of  the  projectile. 

To  obtain  the  second  element,  which  will  give 
a  knowledge  of  all  the  values  of  speeds,  we 
have  recourse  to  the  method  of  previous  range- 
finding  of  the  ground,  explained  previously. 

The  index  of  the  graduated  disk  is  fixed  at 
22°  30'.  The  range  of  any  point  whatever  on 
the  ground  forward  of  the  avion  is  found — a 


Copyright  by  Underwood  &  Undprwooil. 

Bombs  in  the  fuselage  of  an  aeroplane. 


DROPPING  BOMBS  FROM  AEROPLANES 


87 


A  100  11).  bomb  dropped  by  a  Zeppelin. 

route  perpendicular  to  the  one  followed,  a  river, 
a  house,  the  edge  of  a  wood.  This  point  is 
caught  in  the  circle  formed  by  the  air-bubble 
and  followed  while  turning  the  disk  until  the 
index  falls  into  the  notch  at  the  dead  point;  at 
this  instant  the  seconds  chronograph  is  re- 
leased and  the  terrestrial  point  continues  to  be 
followed  in  the  range-finder  until  the  0°  of  the 
disk  is  checked  at  the  dead  point.  The  chrono- 
graph, immediately  stopped,  gives  a  number 
of  seconds  which,  when  found  upon  the  chart 
in  the  line  of  altitude,  indicates  the  speed  of  the 
avion  with  respect  to  the  ground  and  the  sight- 
ing angle  to  make  use  of,  for  example,  10°. 

The  index  is  immediately  set  at  the  number 
of  degrees  of  the  sighting  angle,  i.e.,  10°.  The 
observer  is  ready  to  operate.  About  2  or  3  km. 
before  flying  over  the  object  the  latter  is  caught 
in  the  field  of  vision,  then  in  the  circle  of  the 
bubble.  At  this  instant  the  route  corrector  op- 
erates and  the  galvanometer  indicates  to  the 
pilot  whether  he  is  following  a  route  which  will 
make  the  avion  pass  directly  above  the  object. 

At  the  precise  moment  when  the  index  fixed 
at  the  number  of  degrees  of  the  sighting  angle 


falls  into  the  notch  at  the  dead  point,  i.e.,  at 
the  moment  when  the  finder  aims  with  an  angle 
of  10°,  the  bombardier  operates  the  bomb  re- 
leaser and  the  bombs  fall  toward  the  object. 

Throughout  the  whole  bombardment  the  pilot 
must  keep  his  craft  strictly  head  on  to  the  wind ; 
the  air-bubble  must  be  kept  rigorously  in 
the  center  of  the  ocular,  the  play  of  the 
prism  alone  serving  to  seek  the  object. 

This  Goerz  range-finder  is  of  an  elementary 
simplicity  for  any  one  who  has  manipulated  it 
in  a  few  brisk  actions.  Its  movable  prism  en- 
ables the  object  to  be  found  with  ease,  and  its 
annular  bubble  permits  it  to  be  immediately 
centered  in  the  vertical  position.  Marvelously 
constructed,  it  appears  to  show  marked  prog- 
ress over  all  previously  made  range-finders. 

It  eliminates  errors,  except  from  new  and 
practically  incalculable  elements,  such  as  varia- 
tions of  forces  and  directions  of  the  wind  be- 
tween the  altitude  at  which  the  sighting  is  done 
and  the  ground,  or  when  it  becomes  impossible 
to  keep  the  avion  head  on  toward   the  wind. 


American-made    Barlow    aircraft    bombs.      Photo    courtesy 
New  York   Times  &  Western  Newspaper   Union 


88 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


The  aim  being  at  times  scientifically  perfect, 
as  the  application  of  a  method  derived  from 
calculations,  does  it  follow  that  the  bombs  will 
fall  directly  upon  the  objects  aimed  at?  Re- 
sults loudly  proclaim  a  negative.  Hundreds 
of  bombs  discharged  on  railway   stations,   on 


famous  ironworks,  on  important  aviation  ter- 
rains, have  been  without  result,  except  for  a 
few  shell  "funnels"  in  the  ballasts,  a  few  labor- 
ers killed,  some  holes  in  hangars.  Range-find- 
ing is  a  delicate  task  to  execute  in  an  avion  sur- 
rounded by  bursting  shells. 


^Memoranda : 


The  master  of  the  air.     A  Voisin  armed  bombardment  machine  equipped  with  aircraft  gun  of  large  caliber  photographed  in  mid- 
air.    This  machine  is  equipped  with  a  Canton-Unne  motor. 


CHAPTER  IV 

BATTLEPLANES  AND  AIRCRAFT  GUNS— THE  DOMINANT  FACTORS  IN 
MAINTAINING  THE  SUPREMACY  OF  THE  AIR 


Supremacy  in  the  air,  the  all  important  fac- 
tor which  leads  to  victory  on  land  and  sea,  de- 
pends greatly  on  battleplanes  and  aircraft 
guns. 

About  twenty  per  cent,  of  the  service  aero- 
planes used  by  the  warring  nations  at  present 
are  the  very  fast  avians  de  chasse  or  pursuit  ma- 
chines used  exclusively  for  fighting;  seventy 
per  cent,  are  the  slower  types  used  for  regulat- 
ing artillery  fire,  aerial  photography,  scouting, 
and  in  connection  with  infantry  and  cavalry 
operations;  five  per  cent,  are  the  slower,  large 
bombing  aeroplanes.  All  of  these  aeroplanes 
carry  machine  guns ;  some  carry  cannons. 


Proportions  of  Different  Types  of  Armed 
Aeroplanes  in  the  Air  Service 

The  proportions  vary  continually  in  accord- 
ance with  developments,  and  the  future  will  see 
an  increase  in  the  number  of  bombing  machines, 
with  possibly  an  increase  of  fighting  machines. 
Raiding  from  now  on  is  to  be  carried  out  more 
and  more  extensively,  and  in  connection  with 
the  protection  of  bombing  planes,  as  well  as  the 
protection  of  artillery  "spotters"  and  photog- 
raphy planes,  aerial  fighting  will  increase. 

Pursuit  machines  will  always  be  needed  to 
fight  enemy  aviators,  but  the  practice  of  send- 


39 


40 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


ing  pursuit  machines  to  protect  the  artillery 
spotters  and  photography  planes  will  grow 
less  and  less,  because  it  is  more  economical  to 
employ  large  machines  capable  of  carrying  two 
or  more  guns  and  to  defend  themselves. 

Otherwise  it  is  hard  to  protect  a  plane  with 
less  than  four  to  six  fighting  machines.  To  pro- 
tect themselves  these  planes  must  carry  from 
three  to  four  guns.  JNIany  a  photography 
plane,  equipped  with  only  one  gun,  has  been 
brought  down  by  an  enemy  aviator  who  darted 
at  it  suddenly  and  riddled  it  with  shots  while 
the  observer  was  taking  photographs  and  did 
not  see  it  approach. 

Therefore  a  change  is  taking  place  toward 
larger  machines  to  do  this  work,  which  are  ca- 
pable of  carrying  three  to  four  guns. 


The  Five  Fundamental  Factors  in  Maintain- 
ing Supremacy  in  the  Air 

The  five  fundamental  factors  in  maintaining 
supremacy  in  the  air  are: 


(1)  Speed. 

(2)  Position  of  the  aeroplane. 

(3)  Skill  in  piloting  the  aeroplane  and  in 
manipulating  the  guns. 

(4)  Number  of  aeroplanes. 

(5)  Destructiveness  of  the  projectiles. 

Speed  is  incontestably  the  most  important 
factor.  The  value  of  position  as  a  command- 
ing factor  was  first  demonstrated  by  the  fa- 
mous German  aviators.  Captains  Boelke  and 
Immelmann,  who  would  climb  high  and  take  a 
position  as  near  as  possible  to  a  cloud.  There 
they  would  wait  for  an  Allied  aeroplane,  then 
dive  down  towards  it,  firing  the  machine  gun 
at  the  same  time.  If  they  missed  their  prey, 
they  would  not  attempt  to  challenge  the  Allied 
aviators  or  to  manceuver  to  a  commanding  posi- 
tion and  give  battle.  Failing  in  their  first  dive, 
they  would  land  and  go  up  again  later  to  try  it 
all  over.  It  cost  the  Allies  a  great  many  avia- 
tors and  aeroplanes  before  thej'  found  out  the 
value  of  position  as  a  fundamental  factor  in 
maintaining  supremacj'  in  the  air. 


A  37  millimetre   Hotchkiss  cannon   mounted   on  tt   French   "\'oisin"   battleplane. 


BATTLEPLANES  AND  AIRCRAFT  GUNS 


41 


The  famous  French  aviator  Vedrines  examining  the  two  guns  of  a  German  battleplane,  which  are  so  mounted  that  they  can  be  shot 

in  a  half  circle  and  up  and  down — -through  the  hole  in  the  fuselage. 


Skill  is  an  important  factor,  and  often  makes 
it  possible  for  an  aviator  whose  machine  makes 
five  miles  less  than  his  adversary  to  fight  on  an 
equal  basis. 

Number  makes  up  for  lack  of  speed  or  posi- 
tion. Having  two  or  three  machines  to  the 
enemy's  one,  makes  up  for  the  handicap  due  to 
lack  of  speed. 

Destructiveness  of  projectiles  is  a  very  im- 
portant factor.  The  bullet  of  a  machine  gun 
must  strike  either  the  pilot,  or  the  propeller,  or 
the  motor,  or  the  gas  tank,  or  the  control  wires, 
to  put  the  machine  hors  de  combat.  The  shell, 
on  the  other  hand,  will  put  the  machine  hors  de 
combat  if  it  strikes  practically  any  part  of  the 
machine. 

Types  of  Aeroplanes  and  Their  Armament 

The  types  of  aeroplanes  used  by  the  warring 
countries,    and    their    armament,    have    been 


changing  continually.     At  the  date  of  writing, 
the  following  types  are  used: 

Avions  de  Chasse  or  Combat  Machines 

(1)  The  "Spad"  carrying  one  or  two  pas- 
sengers. A  number  of  these  machines  have,  un- 
fortunately, fallen  in  the  hands  of  the  Germans, 
so  we  may  say  that  their  horse-power  ranges 
from  150  h.p.  to  250  h.p.  and  are  equipped 
with  Lewis  and  Vickers  machine  guns. 

They  are  used  extensively  by  the  French. 

(2)  The  "Nieuport,"  one  passenger, 
equipped  with  one  110-horse-power  Le  Rhone 
motor,  capable  of  a  speed  of  150  kilometers  per 
hour;  equipped  with  two  and  three  Vickers  or 
Lewis  machine  gun  synchronized  to  shoot 
through  the  propeller. 

(3)  The  "Avro,"  carrying  one  or  two  pas- 
sengers, equipped  with  one  lOO-horse-power 
Gnome  motor,  carrying  one  or  two  gims. 


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The   A.  E.  G.   1917   single  motored   type  of  German   biplane, 
equipped  with  a  175  h.p.  Mercedes  motor. 


Avions  Types  "Corps  d'arme" — Used  for 
Spotting  Artillery  Fire,  Aerial  Pho- 
tography, Etc. 

(4)  The  "Caudron"  G-4;  pilot  and  ob- 
sen'cr;  equipped  with  two  80-horse-power  Le 
Rhone  motors,  Lewis  and  Vickers  guns  forward 
and  rear. 

(5)  The  "Caudron"  G-6;  two  passengers; 
equipped  with  two  110-horse-power  La  Rhone 
motors,  carrying  one  machine  gun  forward  and 
one  in  the  rear. 

(6)  "Dorand"  A-R;  two  passenger; 
equipped  with  one  150-horse-power  Hispano- 
Suiza   motor   or   a    170-horse-power   Renault, 


carrying  one  Vickers  gun  forward,  and  two 
Lewis  guns  in  the  rear. 

(7)  Farmaii;  pusher  type,  two  passenger; 
equipped  with  one  170-horse-power  Renault 
motor,  carrying  one  or  two  Lewis  guns  for- 
ward. 

(8)  Morane  Parasol;  two  passenger;  one 
110-horse-power  La  Rhone  motor,  mounting 
one  Lewis  gun  in  the  rear. 

(6)  Caudron  R-4;  three  passengers; 
equipped  with  two  150-horse-power  Hispano- 
Suiza  motors,  with  two  Vickers  guns  mounted 
forward  in  turrets,  and  two  Lewis  guns  in  the 
rear. 

(9)  Letort;  equipped  with  two  150-horse- 
power  Hispano-Suiza  motors;  two  Vickers 
guns  mounted  forward  in  turrets  and  two 
Lewis  guns  in  the  rear. 

(10)  Moineau;  three  passengers;  one  220- 
horse-power  Samson  motor,  connected  to  drive 
two  propellers;  equijiped  with  two  Vickers 
guns  mounted  forward  in  turrets,  and  two 
Lewis  guns  in  the  rear. 

(11)  Sopmth  TripMue.  This  type  of 
machine  has,  unfortunately,  fallen  in  the 
hands  of  the  enemy,  therefore  we  may  note  its 
existence  as  a  combat  machine  used  by  the 
British. 

(12)  Sopwith     biplane;     two     passenger; 


A    "G-4"    Caudron    biplane,    equipped    with    two    HO    li.p.  I>e   ithone  motors.    The  gun   mounting   is  si-rn   in    front. 


BATTLEPLANES  AND  AIRCRAFT  GUNS 


^8 


The  ofScers  of  a  squadron  of  Voisin  bombing  ma  chines  being  decorated  for  their  successful  raids. 


equipped  with  130-horse-power  Clerget  motor, 
carrying  eight  bombs;  Vickers  machine  gun 
forward,  shooting  through  propeller,  and  one 
Lewis  gun  in  the  rear. 

(13)  Voisin-Peugeot;  two  passenger; 
equipped  with  a  220-horse-power  Peugeot  mo- 
tor ;  carrying  two  Vickers  or  37  millimeter  guns 
forward. 

(14)  Breguet-Michelin;  two  passenger; 
equipi^ed  with  one  220-horse-power  Peugeot 
motor;  mounting  two  Vickers  or  37  millimeter 
machine  guns  forward. 

(15)  Farman;  pusher  type,  two  passenger; 
equipped  with  one  170-horse-power  Renault 
motor,  mounting  one  Lewis  gun  forward, 

(16)  The  Caproni;  the  various  tyjies  men- 
tioned in  the  chapter  on  "Warplanes  for  Bomb- 
ing and  Torpedo  Launching,"  are  with  Fiat 
machine  guns  and  cannons  and  Davis  non-re- 
coil guns.  So  are  the  Pomilio  SIA,  Sa- 
voya-Verduzio  and  ]Macchi  machines. 

At  date  of  writing,  the  British,  French,  and 
Germans  can  be  said  to  have  more  or  less  the 


same  types  of  aeroplanes,  with  the  same  amount 
of  armament.  As  a  matter  of  fact,  the  warring 
nations  are  never  far  from  each  other  in  either 
types  or  armament,  because  as  fast  as  they  cap- 
ture each  other's  machines  and  find  important 
improvements,  they  copy  them. 

Pursuit,  or  Combat  Machines 

Among  the  comparatively  new  machines  of 
the  British  Royal  Flying  Corps,  there  is  the 
Soptiith  triplane,  which  has  given  such  a  good 
account  of  itself  as  a  combat,  or  pursuit  ma- 
chine on  the  Western  fronts.  Other  machines 
of  this  type  are  the  De  Haviland  scout  biplane, 
a  "pusher"  with  a  fixed  gun  in  front,  and  the 
Vickers  biplane,  two  passenger,  equipped  with 
Beardmore  or  Clerget  motors. 

The  German  combat  machines  include  the 
Ago,  the  Fokker,  the  Halberstadt,  the  Roland, 
which  are  equipped  with  Mercedes,  Oberunsel 
(rotary),  Benz,  and  Argus  motors  of  165  to 
175  horse-power.  They  are  armed  with  Para- 
beilum  or  Vickers  and  Lewis  guns. 


"Two  Tails,"  twin  fuselage  simple  mo- 
tored German  Ago  biplane  equipped  with 
a  150  h.]).  Benz  motor  and  Parabellum 
and  Vickers  guns. 


44 


TEXTBOOK  OF  MILITARY  AEROXAUTICS 


The  Gentian  "Rump' 


liipbmr,   I  «(i-seater,  equipped  with  two  iruns. 


The  two  smallest  machines,  the  Halberstadt 
and  the  Albatros  Bii,  are  single  seaters,  all  the 
others  being  two-seaters.  Where  the  gunner 
occupies  the  rear  cockpit,  it  is  found  that  in 
many  cases  the  pilot  is  equipped  with  a  syn- 
chronized gun,  fired  forward  and  sighted  by 
steering  the  machine  itself.  The  same  applies 
to  the  single-seaters.  Some  of  the  single- 
seaters  are  equipped  with  two  synchronized 
guns,  fired  directly  in  front.  The  top  wing  of 
the  Albatros  Bii  is  28  feet,  4>  inches,  the  bot- 
tom wing  26  feet,  nine  inches ;  gap,  5  feet,  three 
inches;  chord,  five  feet,  nine  inches;  length  over 
all,  24  feet.  The  measurements  of  the  Hal- 
berstadt are:  top  wing,  28  feet,  6  inches;  bot- 
tom wing,  26  feet;  gap,  four  feet,  6  inches; 
chord,  5  feet;  length,  24  feet. 

The  measurements  of  the  Nieuport  and  the 


Spad  are:  Nieuport;  top  plane,  24  feet  6  inches; 
bottom  plane,  23  feet;  chord,  top  plane,  3  feet 
11  inches;  bottom  plane,  2  feet  4  inches;  gap,  4 
feet  2  inches  to  3  feet  ii  inches;  length,  18  feet 
6  inches.  Spad  type  5 VII,  one  passenger;  top 
plane,  25  feet  8  inches;  chord,  4  feet  7  inches; 
gap,  4  feet  10  inches;  length,  20  feet. 

The  speed  of  these  machines  varies  with  the 
horse-power,  ranging  from  95  miles  to  125  miles 
per  hoiu"  high  speed,  to  from  56  miles  to  80 
miles  slow  speed.  The  climbing  speed  ranges 
from  4000  to  10,000  feet  in  ten  minutes. 

Owing  to  lack  of  demand,  few  machines  of 
this  type  were  built  in  the  United  States  until 
recently.  But  efficient  types  existed.  The  Cur- 
tiss  wireless  scout  of  1915-16  was  followed  by 
the  Curtiss  triplane,  the  characteristics  of  wliich 
cannot  be  made  public. 


The  Italian  I'onillio  curiibat  plane,  salU  tu  be  tlie  fu«tei>t  buttlcplune  in  vxititence.     (Uliieiiil   Ualian  Photo.) 


BATTLEPLANES  AND  AIRCRAPT  GUNS 


45 


The   German   "Spatl,"   tlie 


MflTelU-.s     lliolill'cil     "\ll];lil 


nized  to  shoot  through  the  propeller. 


It  carries  two  Maxim  guns  which  are  synchro- 


The  Triplane — A  Scientific  Solution  of  the 

Problem  of  Getting  Speed  and  High 

Factor  of  Safety 

The  triplane  solves  the  problem  of  getting 
high  speed  with  the  low  landing  speed  and  high 
factor  of  safety.  The  additional  plane  affords 
sufficient  increase  in  carrying  capacity  to  lift  the 
additional  weight  of  stronger  construction,  and 
also  makes  slower  landing  possible,  without 
much  additional  head  resistance. 

The  battleplane,  while  representing  only  one 
fifth  of  the  types  of  machines  used  in  the  pres- 
ent war,  is  the  key  to  command  of  the  air,  be- 
cause the  skies  must  be  cleared  of  enemy  avia- 
tors before  the  scouts,  bombing,  artillery,  and 
infantry  aeroplanes  can  w^ork  efficiently.  Of 
course,  if  one  side  could  outnumber  the  other 
side,  the  equivalent  of  the  fighting  power  af- 
forded by  the  fast  battleplanes  could  be  obtained 
by  the  advantage  afforded  by  number,  which 
makes  up  for  having  a  few  miles  less  in  speed 
or  less  skilful  aviators. 

But  neither  side  has  been  able  to  outdistance 


the  other  appreciably  in  numbers;  therefore 
command  of  the  air  is  still  decided  by  speed,  the 
pilot's  skill,  and  the  pilot's  ability  to  gain  an 
advantageous  position,  like  the  famous  Captain 
Boelke,  who  used  "position"  as  a  winning  fac- 
tor. 

As  a  general  rule,  however,  speed  is  the  basic 
factor  for  achieving  command  of  the  air. 
Hence  every  effort  is  made  to  get  speed,  and  the 
factor  of  safety  in  construction  is  only  given 
second  consideration,  when  it  is  considered  at 
all. 

Triplane  Safe,  Even  if  Wing  Is  Shot  Away 

The  triplane  is  safe,  even  if  a  wing  is  shot 
away;  the  remaining  wings  will  support  it  for 
the  rest  of  the  flight  under  any  normal  condi- 
tions. A  biplane  usually  collapses  soon  after 
a  wing  has  been  shot  away,  and  a  monoplane 
collapses  immediately. 

Triplane  construction  removes  the  speed 
limitations  imposed  upon  the  small  biplanes  and 
monoplanes    by   their    limited    lifting   power; 


46 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


A  squadron  of  Xicuport  combat  machines. 


therefore  speed  can  be  increased  to  close  to  150     ment  just  in  time  to  avoid  a  collision.     One  of 


miles,  going  beyond  the  margin  of  safety  of 
the  average  biplane  battleplane. 

Battleplanes    that    Collapsed    in    the    Air — 
Loss  of  Factor  Safety  Not  Compensated 

A  recent  despatch  stated  that  German  bat- 
tleplanes have  been  collapsing  in  the  air,  at 


the  wings  of  the  British  aeroplane,  however, 
scraped  one  of  the  German's  wings,  whereupon 
the  latter  began  to  fall.  The  British  pilot 
dived  after  him  and  was  startled  to  see  the 
German's  damaged  wings  fly  completely  off, 
while  the  tail  dragged  as  if  its  back  was 
broken." 

The  causes  are  evident.     In  the  struggle  for 


times  without  being  hit,  often  when  but  slightly     additional  speed,  there  has  been  sacrificed  the 


damaged.     The  despatch  follows  in  part: 

"With  the  British  armies  in  France,  via  Lon- 
don— British  pilots  continue  to  bring  in  ac- 
counts of  German  aeroplanes  breaking  to  pieces 
in  the   air  soon   after   being  attacked.     That 


factor   of   safety.     The   machines   are   merely 
shells  of  machines. 

Triplane  construction  is  a  scientific  solution 
of  getting  greater  speed  and  high  factor  of 
safety,  but  there  is,  of  course,  nothing  to  pre- 


tendency  has  been  notable  for  more  than  a  fort-  vent  cutting  down  the  factor  of  safety,  so  as  to 
night.  Once  shot  out  of  control,  the  German  get  a  few  miles  more  in  speed, 
aeroplanes  have  lost  their  wings,  tails,  and  other  Considering  the  fact  that  low  factor  of  safety 
gear  to  such  an  extent  that  when  they  finally  involves  the  loss  of  aviators  and  machines 
crash  on  the  ground,  very  little  wreckage  can  through  accidents,  as  well  as  through  machines 
be  seen.  collapsing  when  slight  damages  are  inflicted  by 

"A  British  pilot  recently  flew  at  an  enemy    gun-fire  or  other  causes,  and  that  this  loss  in- 
machine  head-on,  manoeuvering  at  the  last  mo-     volv^es  a  decrease  of  skilled  aviators  and  number 

of  machines,  the  writer  contends  that 
this  loss  is  not  compensated  for  by  the 
advantages  afforded  by  the  slight  gain 
in  speed.  As  already  pointed  out, 
while  speed  is  the  most  important  fac- 
tor in  maintaining  supremacy  in  the 
air,  five  miles  or  so  less  speed  than 
that  of  the  adversary'  can  be  compen- 
sated for  by  having  skilful  aviators,  or 
The  Gennan  "Koiaiui"  two  siaiir,  so  imiit  thai  the  i>iiot  .scc-s  ovlt  tho    jj  greater  nimibcr  of  aviators  and  aero- 

npprr  plane  and  hag  but  a  single  stmt,  like  the  "wireless"  Curtiss  of  1916.         . 

It  U  equipped  with  •  140  h.p.  Bcnz  motor.  plones. 


BATTLEPLANES  AND  AIRCRAFT  GUNS 


47 


Triplanes   being  assembled   at   one   of   tlie   Sopwith   factories   in   Eiighiiul,   being   inspected   by   tiie   King  and   Queen   of   England. 

These  triplanes  are  equipped  with  130  h.p.  Clerget  motors. 


Large  Aerial  Destroyers 

The  larger  army  machines  are  four:  The 
"Moineau,"  the  "Voisin-Peugeot,"  the  "  Bre- 
guet-JNIichelin"  and  the  "Farman."  These 
may  be  called  "destroyers,"  no  matter  what  they 
may  be  used  for.  The  most  popular  British 
machine  of  this  type  is  the  "Handley-Page." 
This  machine  is  equipped  with  two  twelve- 
cylinder  Rolls-Royce  cylinders  of  280  horse- 
power each;  the  top  wing  has  a  98-foot  span; 
the  lower  wing,  65  feet.  It  has  mountings  for 
three  Lewis  guns. 

The  Germans  have  several  machines  of  this 
type.  The  twin  "A.  E.  G."  (manufactured  by 
the  Allegemeine  Electricitats  Gesellschaft)  is  a 
three-seated  tractor  biplane  with  two  i80-horse- 
power  Mercedes  motors.  Like  all  machines  of 
this  type,  including  the  French,  British,  Italian, 
and  Russian,  it  is  equipped  with  two  pairs  of 
wheels.  Its  armament  consists  of  Maxim  guns 
forward  and  rear,  and  a  bomb-dropping  device 
in  front  of  the  passenger's  seat. 

The  "A.  G.  O.,"  a  twin-bodied  pusher, 
usually  equipped  with  a  single  Bentz  175-horse- 
power  motor;  the  latest  are  equipped  with  a 


Bentz  220-horse-power  motor.  It  carries  two 
guns  mounted  on  turrets  in  front. 

The  twin-motored  520-horse-power  "Gotha" 
is  a  three-passenger  biplane  usually  equipped 
with  two  six-cylinder  Mercedes  motors  of  260 
horse-power.  The  wings  are  76  feet  in  span. 
The  length  of  the  machine  is  38  feet.  It  is 
usually  armed  with  Maxim  guns  forward  and 
rear,  and  it  fires  downward  through  a  hole  in 
the  rear  fuselage.  It  is  equipped  with  three 
bomb-dropping  devices  and  carries  144  bombs. 

In  the  smaller  German  armed  machines  not 
already  mentioned,  are  the  following:  The 
"Pfalz"  monoplane,  equipped  with  a  100-horse- 
power  Obei-rusael  rotary  motor.  Its  arma- 
ment consists  of  two  fixed  guns,  mounted  on 
each  side  of  the  pilot  and  firing  through  the 
propeller. 

The  "Fokker"  is  also  equipped  with  two 
Maxim  guns  firing  through  the  propellers. 

The  "Albatross  C-3";  the  "Aviatik";  the  "L. 
V.  W.";  and  the  "Rumpler"  represent  the  aver- 
age type  of  German  biplanes.  The  size  of  the 
top  wing  is  from  39  to  42  feet,  10  inches;  the 
bottom  wings  from  35  to  38  feet ;  and  the  length 
from  26  feet  3  inches  to  27  feet;  thev  are  all 


48 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


A   view  of  the  French  "Spacl"  equipped  with  the   Hispano-Suizti  100  h.j).  motor  and   Nickers  gun  in  front  and  Lewis  in  the  rear. 


armed  with  Maxim  guns  shooting  through  the 
propellers;  some  carry  Maxim  or  Parabellum 
guns  mounted  on  turrets  in  the  rear.  They  are 
equipped  with  from  two  to  four  bomb-dropping 
apparatuses. 

In  the  United  States  there  are,  at  date  of 
writing,  about  a  dozen  types  of  twin-motored 
aeroplanes,  all  suitable  for  arming;  but  until  the 
United  States  entered  the  war,  no  steps  were 
taken  to  arm  the  machines  with  machine  guns 
or  equip  them  with  bomb-dropping  devices. 

Aeroplane  Guns  and  Cannon 

The  aeroplane  guns  and  cannon  employed 
to-day  were  developed  in  the  year  1912-1914 
and  perfected,  as  far  as  their  perfection  goes, 
during  the  war.  Considered  from  the  stand- 
point of  the  guns  of  six  years  ago,  the  aeroplane 
guns  of  to-day  are  marvelously  efficient. 

The  most  extensively  used  aeroplane  guns 
of  small  caliber  are  the  Lewis  and  the  Vickers 
by  the  Allies,  and  the  Maxim  and  the  Para- 
bellum by  the  Germans.  The  I>ewis  macliine- 
^n  is  an  air-cooled,  gas-operated,  magazine- 
fed  gun,  weighing  about  26  pounds  with  the 
jacket,  or  18  pounds  without  the  jacket.  The 
gun  is  at  present  used  almost  entirely  without 


the  jacket,  without  any  loss  of  efficiency.  Its 
extreme  mobility  makes  it  a  most  efficient  gun 
for  aeroplane  work,  being  capable  of  operating 
in  any  position,  firing  straight  up  or  straight 
down,  or  in  any  direction.  The  speed  of  get- 
ting into  action  and  the  ability  to  function  auto- 
matically in  any  position  are  due  to  the  use  of 
detachable,  drum-shaped,  rotating  magazines, 
each  magazine  holding  47  or  97  cartridges. 
^\Tien  a  magazine  is  latched  on  the  magazine 
post,  it  temporarily  becomes  a  part  of  the  gun, 
requiring  no  further  attention  until  empty, 
when  it  is  snatched  off  and  another  snapped  on, 
as  quickly  as  an  empty  magazine  is  dropped  out 
of  an  automatic  pistol  and  a  loaded  one  inserted. 
Further  details  of  this  gun  will  be  given  later, 
with  the  detailed  description  of  its  construction. 
The  Vickers  is  a  water-cooled,  recoil-oper- 
ated, belt-fed  machine-gun.  Like  the  Lewis 
gun,  it  is  capable  of  being  fired  at  the  rate  of  300 
to  .500  shots  per  minute,  maximum.  Its  advan- 
tage over  the  Lewis  gim  is  that  it  is  capable  of 
being  fired  continuously  up  to  .'jOO  shots, 
whereas  the  I^ewis  requires  changing  of  maga- 
zines after  97  shots.  On  the  other  hand,  it  has 
the  disadvantage  of  being  belt-fed,  so  it  does  not 
afford  the  mobility  which  the  Lewis  gun  af- 
fords.    The  water-cooling  in  the  Vickers,  like 


BATTLEPLANES  AND  AIRCRAFT  GUNS 


49 


the  air-cooling  device  in  the  Lewis,  has  been  dis- 
pensed with  for  aerial  work,  as  unnecessary. 

Therefore,  in  most  of  the  French  and  British 
planes  one  finds  the  Vickers  gun  fixedly 
mounted  in  front,  and  the  pilot  points  the  aero- 
plane at  the  enemy,  instead  of  pointing  the  gun. 
The  Lewis  guns  are  mounted  in  the  rear  or  in 
front,  on  mobile  or  fixed  mountings.  The  Ger- 
man Maxim  is  practically  the  same  as  the  Vick- 
ers gun  used  by  the  Allies.  The  Lewis  shoots 
.33  ammunition,  and  the  Vickers  shoots  .30  am- 
munition. 

The  Colt,  a  gas-operated,  air-cooled,  belt-fed, 
automatic  gun,  was  used  as  an  aeroplane  gun  in 
the  beginning  of  the  war,  but  there  are  few  in 
use  now.  That  is  also  true  of  the  Hotchkiss 
and  the  Benet-Mecier,  which  is  a  modification 
of  the  Hotchkiss. 

All  belt-fed  guns  are  subject  to  jamming, 
particularly  when  cotton  is  used  instead  of  linen 
webbing,  but  in  the  air  the  one  thing  to  be  feared 
is  jamming,  due  to  the  fact  of  the  tremendous 
wind-jDressure  on  the  belt.  The  present  method 
of  mounting  Vickers  on  aeroplanes  has  prac- 
tically solved  this  problem. 

The  Fiat  aircraft  gun  used  by  Italy  is  in  the 
order  of  the  Vickers,  and  shoots  400  shots  per 
minute. 

Large  Aeroplane  Guns 

Details  about  the  larger  aeroplane  guns  have 
been  kept  secret,  but  there  are  many  in  use,  there 


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WsaM^-S"., 


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1  reudi  isieupoit  "Avion  de  cliasse"  flying  over  a  stretch  of 
"no    man's    land"    in    France. 


being  squadrons  of  large  aeroplanes  equipped 
with  them.  A  Hotchkiss  one  pounder,  or  one- 
inch  gun,  has  been  used  in  France  and  England. 
A  Vickers  pom-pom,  or  one  inch,  weighing  180 
or  190  pounds,  is  reported  as  giving  good  re- 
sults and  the  Fiat  37  millimeter  has  been  a  great 
success. 

The  Davis  gun,  the  invention  of  Com- 
mander Davis  of  the  United  States  Navy,  made 
in  one-inch  and  three-inch  sizes,  is  a  most  re- 
markable weapon.  The  two  pounder,  six 
pounder,  and  12  pounder  are  entirely  non-recoil 


The   French   "Corps   d'Armee"   type,   "Letort"  battleplane   equipped  with  two  ISO  h.p.   Hispano-Suiza  motor.",   and  mounting  two 

Lewis  and  two  Vickers  guns. 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


-1 


The  three  motored  Italian  Caproni  biplane  equipped  with  three  Frasohini  motors. 


guns.  The  two  pounder  is  10  feet  long,  weighs 
75  pounds,  shoots  1.575  projectile  with  a  muz- 
zle velocity  of  1200  feet  per  second.  The  three- 
inch  Davis  weighs  130  pounds.  It  fires  a  pro- 
jectile weighing  between  12  and  13  pounds  at 
a  guaranteed  muzzle  velocity  of  1000  feet  per 
second,  but  it  has  shown  a  velocity  of  1200  feet 
in  tests. 

Another  American  aeroplane  gun  is  the 
Driggs  one-pounder,  now  being  manufactured. 
It  fires  one  pound  shells  at  the  rate  of  fifty  per 
minute,  weighs  one  hundred  and  sixty  pounds, 
including  twenty  rounds  of  ammunition,  and 
the  recoil  pull  amounts  to  six  hundred  pounds. 

The  Driggs  Aeroplane  Machine  Gun,  an- 
other new  American  gim,  is  similar  to  the  Lewis 
gun  in  that  it  has  a  self-contained  magazine, 
which  holds  one  hundred  cartridges,  and  the  gun 
is  operated  by  recoil,  instead  of  by  gas. 

The  larger  guns,  while  not  so  mobile  as  the 
smaller,  have  greater  destructive  power  and  can 
reach  further  than  the  smaller  guns.  When 
they  hit  a  plane,  almost  any  part  of  it,  they  are 
almost  certain  of  wrecking  it,  whereas  the  bul- 
lets of  smaller  guns  are  only  effective  when  they 
hit  the  pilot  or  the  vulnerable  parts  of  the  aero- 
plane. 

Problems  of  Armoring — Vulnerable  Parts  of 
the  Aeroplane 

So  far  no  progress  has  been  made  in  the  ar- 
moring of  aeroplanes.  To  have  an  effective  ar- 
mor to  protect  the  pilot  and  the  vulnerable  parts 


would  involve  prohibitive  weight,  which  would 
cut  down  the  efficiency  of  the  aeroplane  beyond 
the  safety  point.  The  vulnerable  parts  of  the 
aeroplane  are:  (1)  the  pilot;  (2)  the  gasoline 
tank;  (3)  the  propeller ;  (4)  the  motor;  (5)  the 
control  wires.  Of  course,  the  pilot  could  be 
encased  in  a  steel  cabin,  but  that  would  limit  his 
mobility,  and  the  enemy  aviator  could  fly  close 
and  hit  the  other  vulnerable  parts  of  the  aero- 
plane without  interference.  The  gas-tank  and 
the  motor  can  be  armored  to  some  extent  with- 
out great  additional  weight,  but  when  the  mat- 
ter is  considered,  it  always  appears  that  the 


One  of  the  Fokkers  hrou^tlit  down  l>y  a  French  aviator. 
This  shows  the  armored  liody  and  the  Maxim  pni  mounted  on 
top.  General  fioiiraiid,  the  late  Freneh  Conmiandcr-in-Chief 
at  the  Dardanelles,  is  standing  by  tlie  propeller. 


BATTLEPLANES  AND  AIRCRAFT  GUNS 


51 


The  French  Br^guet-Michelin  bombing  biplane  equipped   with  a  230   Peugeot   motor  and   two  guns 


weight  involved  could  be  invested  to  better  ad- 
vantage in  adding  a  gun,  thereby  increasing  the 
armament  of  the  aeroplane  by  one  unit. 

The  proj^eller  and  the  wires  cannot,  of 
course,  be  armored.  Air  fighters  always  aim  to 
hit  the  pilot  of  a  machine.  The  gasoline  tank, 
the  motor,  the  propeller,  and  other  parts  of  the 
aerojilane  get  hit  as  a  result  of  the  effort  of  the 
gunner  to  hit  the  pilot.  Next  to  the  pilot,  the 
propeller,  the  gas  tank,  and  the  motor  are  the 
vulnerable  parts  of  an  aeroplane  which  get  hit 
oftener.  Only  occasional^  are  aeroplanes 
brought  down  through  the  wrecking  of  the  con- 
trols or  other  parts  of  the  aeroplanes.  Many 
aeroplanes  come  down  at  the  end  of  a  few  hours' 
flight  with  several  hundred  holes  in  their  planes, 
made  by  bullets  from  hostile  aeroplanes  and  bits 
of  shrapnel  from  the  anti-aircraft  guns. 

Bullets  vs.  High  Explosive  Shells 

A  bullet  striking  the  strut  or  the  rib  of  an 
aeroplane  merely  leaves  a  hole,  but  very  rarely 


does  more  damage  than  that.  A  shell  striking 
the  same  part  will  wreck  the  plane.  Hence  the 
shell  has  its  advantages.  The  mobility  of  a 
larger  gun  would,  of  course,  be  less  than  the 
mobility  of  the  smaller  gun,  but  that  is  compen- 
sated by  the  destructiveness  of  the  shot. 

However,  the  necessity  of  having  rapid  fire 
in  aerial  fighting  precludes  the  possibility  of  the 
larger  gun  replacing  the  smaller  gun.  One 
supplements  the  other.  Another  thing;  it 
would  not  be  possible  to  mount  the  larger  gun 
so  as  to  fire  through  the  propeller  with  the  syn- 
chronizing device.  A  shell  hitting  the  pro- 
peller would  wreck  it,  and  possibly  result 
in  tearing  the  motor  loose,  breaking  the  gaso- 
line pipes,  and  setting  the  machine  on  fire. 
With  the  smaller  gun,  a  bullet  "hanging 
fire"  and  striking  the  propeller  seldom  does 
more  than  make  a  hole  in  or  splinter  the  pro- 
peller. However,  hardly  more  than  one  bullet 
in  5000  hits  the  propeller.  In  firing  with  the 
synchronizing  device,  it  releases  a  shot  at  every 


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four  turns  of  the  propeller,  permitting  the  fir- 
ing of  about  300  shots  per  minute. 

Explosive  shells  are  used  with  Lewis,  Vickers, 
Fiat,  Parabellum  and  JNIaxim  guns. 

Fast  vs.  Slow  Muzzle  Velocity 

Fast  muzzle  velocity  has  certain  advantages, 
but  has  the  disadvantage  of  involving  greater 
weight,  due  to  the  necessity  of  having  a  stronger 
gun  to  withstand  the  additional  discharge,  and 
stronger  mounting  to  withstand  the  greater 
recoil. 

The  same  result  can  be  obtained  with  slow 
muzzle  velocity  by  aiming  ahead  of  the  target. 
In  the  beginning  of  the  war,  there  being  no 
precedent  in  aerial  gunnery,  considerable  con- 
fusion resulted  and  there  was  accepted  an  ex- 
tremely high  muzzle  velocity.  Then  it  was  de- 
cided that  a  maximum  muzzle  velocity  of  800 
feet  per  second  was  sufficient,  giving  the  de- 
sired results,  but  eliminating  considerable 
weight. 

As  a  general  rule,  outside  of  aeronautics  a 
gun  weighs  one  hundred  times  the  weight  of  the 
projectile.  This  weight  is  necessary  to  give  it 
the  velocity  needed  to  carry  the  projectile  ver- 
tically or  horizontally  over  considerable  dis- 
tances. Shooting  down  from  a  height  only  re- 
quires a  portion  of  that  muzzle  velocity,  the  pro- 
jectile acquiring  velocity  in  its  downward  tra- 
jectory. 


A  Lewis  gun  mounted   on  a   French  avion  cle  combat. 

Recoil;  a  Solved  Problem 

Up  to  the  time  of  the  war,  it  was  feared  that 
the  recoil  of  a  gun  would  affect  the  stability  of 
the  aeroplane.  Even  the  recoil  of  small  ma- 
chine-guns was  feared.  It  is  now  a  solved 
problem  for  large  machines.     It  has  been  found 


The   1917  type   Nieuport  avion  de  rhassc,  rqulpjicd  with   two  Lewis  guns  slioofing  over  the  planes,  and  a  -Vickers  gun  to  slioot 
through  the  pro|)cller.     In  the  rear  can  be  seen  a  "Spad"  and  several  N'ieuports. 


BATTLEPLANES  AND  AIRCRAFT  GUNS 


53 


This  photograph  shows  the  mounting  of 
the  two  Lewis  guns  on  top  of  tlie  plane  and 
one  Vicliers  gun  in  front  of  the  pilot  seat 
of  the  single-seater  Nieuport  biplane. 
French  official  photo,  passed  by  French 
censor.   {Courtesy  of  "Flying.") 


that  aircraft  absorb  the  recoil  of  any  gun  of  a 
size  suitable  for  firing  from  an  aeroplane;  that 
is,  the  aeroplane  acts  as  its  own  recoil  cylinder. 
This  was  first  discovered  in  the  early  part  of 
1914  when  a  small  naval  cannon  was  mounted 
on  the  first  Voisin  gun-plane.  That  fear  proved 
to  be  helpful,  as  it  resulted  in  developing  light, 
efficient  machine-guns  and  cannon. 

Tactics  in  Air  Duels 

For  the  sake  of  avoiding  confusion,  it  is  well 
to  separate  air  duels  into  four  classes,  as  fol- 
lows : 

(1)    Air  Duels   in  Which   Participants   are 
Both  Air  Fighters  Whose  Only  Func- 
tion is  to  Keep  the  Sky  Clear  of 
Enemy  Machines 

The  aviator  having  this  mission  to  perform 
usually  flies  out  with  a  speedy  machine 
equipped  with  from  one  to  three  aeroplane 
guns.  He  flies  as  high  as  he  can  and  remains 
high  until  he  sees  an  enemy  machine.  Then 
he  dives  down  toward  it  and  tries  to  bring  it 
down  by  opening  fire  on  it  as  he  gets  to  firing 
distance,  keeping  up  the  stream  of  fire  until  he 
sees  the  enemy  machine  fall.  If  he  missed  hit- 
ting a  vital  part,  he  must  either  land,  if  he  is 


near  his  own  lines,  or  manoeuver  to  a  point  of 
vantage  to  shoot  at  the  enemy  again,  or  try  to 
rise  vertically  as  quickly  as  possible,  and  ma- 
ncEuver  for  a  high  position  again,  before  the 
enemy  gets  to  the  point  of  vantage  to  open  fire 
on  him. 

The  first  method,  that  of  flying  to  a  height 
and  then  diving  down  upon  the  enemy  machine, 
opening  a  stream  of  fire  on  him,  and  landing 
in  case  of  failure,  was  originated  and  adopted 
by  Immelman  and  Boelke,  the  famous  German 
aviators,  who  brought  down  a  large  number  of 
Allied  aviators  before  their  tactics  were  known. 
But  the  success  of  that  method  is  based  on  fight- 
ing enemy  machines  that  are  operating  over 
one's  territory  and  that  in  itself  is  basically 
faulty,  as  control  of  the  air  means  striking  the 
enemy  aviators  over  the  enemy's  territory,  never 
permitting  the  enemy  aviators  to  come  as  far 
as  one's  own  lines. 

A  very  sound  principle  of  tactics  in  air  duels 
is  to  fly  to  a  height,  and  then  dive  down  on  the 
enemy  aviator,  pouring  a  rain  of  bullets  on 
him.  This  is,  of  course,  the  maneuver  that 
every  aviator  would  like  to  perform.  Being 
above  the  enemy  is  an  advantage.  Unless  the 
enemy  is  hit  and  fluttering  away,  and  needs 
only  a  few  more  shots  to  be  put  hors  de 
combat,  the  practice  is  to  make  a  sharp  turn 


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and  quickly  climb  to  a  height,  and  regain  a 
point  of  vantage  before  the  enemy  can  do  so. 
Having  reached  a  height,  the  pilot  is  again  at 
the  point  of  vantage  from  which  he  can  shoot 
down  on  the  enemy. 

In  aerial  combats,  as  in  naval  combats,  one's 
movements  are  often  changed  by  the  enemy's 
movements.  The  strongest  and  ablest  drives 
the  other  into  "tight  corners"  at  sea.  But  in  the 
air  one  can  fly  over,  under,  and  aroimd  the 
enemy,  and  as  both  combatants  are  flying  at 
tremendous  speed,  which  reaches  1.50  miles  per 
hour  in  dives,  the  combatants  often  fly  about 
for  many  minutes  before  they  get  to  a  point 
of  vantage  from  which  they  can  shoot  at 
the  pilot,  gunner,  or  vulnerable  parts  of  the 
machine. 

(2)    Air  Duels  Between  Combat  Machines 

and  Armed  Photographing,  Spotting, 

or  Bombarding  Machines 

A  duel  between  a  combat  machine  and  an 
armed  photographing,  spotting,  or  bombing 
machine  is  quite  different  from  the  duel  between 
combat  machines.  The  combat  machine  will 
dive  on  the  armed  larger  machine,  which  will  re- 
ceive it  with  upward  fire  from  one  or  more  guns. 
If  the  combat  machine  succeeds  in  hitting  one 
of  the  gunners,  it  only  silences  one  of  the  guns, 
but  still  has  to  deal  with  the  other  gunners  and 
guns.  If  the  aviator  does  not  succeed  in  hit- 
ting one  of  the  gunners,  then  there  is  a  regular 
battery  of  guns  to  shoot  at  him,  and  he  will  need 


A  37  millimeter  gun  mounted  on  a  Voisin-Peugeot  gun  plane. 


all  the  skill  that  he  can  command  to  so  ma- 
noeuver  as  to  avoid  their  fire.  But  while  he 
may  manoeuver  swiftly,  the  enemy  machine  does 
not  manoeuver  so  swiftly ;  it  is  not  necessary,  for 
it  depends  on  driving  away  the  small  combat 
machine  by  sheer  gun-fire  and  skill  in  gun  ma- 
nipulation. In  the  first  year  of  the  war,  when 
few  machines  were  armed  with  aircraft  guns 
and  rifles  and  pistols  were  used  for  aerial  com- 


A  Davis  non-recoil  jiun  mounted 
on  R  British  biittleplane.  Tlie 
three  inch  pun  of  this  type  shoots 
a  15  pounder. 


BATTLEPLANES  AND  AIRCRAFT  GUNS 


56 


A   Ilciuy    Fariuan 


"Lo;pa 


dWr 


uRc'   type,  photographed  as  it  was  passing  another  French  battleplane,  6,000  feet  up. 


bats,  small,  fast  German  machines  attacked  the 
large,  slow,  Russian  Sykorsky  machines  and 
the  Russian  gunners  were  able  to  bring  down 
the  Germans  with  their  rifle-fire  from  the  plat- 
form of  the  Sykorsky  machines. 

(3)  Air  Duels  Between  Large  Armed 
Aeroplanes 

In  air  duels  between  large  armed  aeroplanes 
the  tactics  are  different.  These  types  of  ma- 
chines, being  usually  busy  with  taking  photo- 
graphs, spotting,  or  bomb-dropping,  seldom  go 
to  great  heights;  and  they  are  not  so  well 
adapted  to  diving  and  swift  manoeuvering  as  the 
combat  machines.  But  that  is  where  the  na- 
ture of  the  gun  and  the  marksmanship  are  the 
main  factor  in  deciding  the  victoiy.  As  most 
of  these  large  machines  are  either  twin-motored 
or  are  of  the  pusher  type,  with  the  motor  in  the 
rear,  they  mount  aeroplane  guns  of  large  cali- 
ber in  front,  and  can  shoot  at  the  enemy  from 
front  and  sides.  The  twin-motored  aeroplanes 
also  permit  mounting  guns  in  the  rear,  so  that 
they  can  fight  from  almost  any  angle  of  attack. 
The  employment  of  aerial  gims  of  large  caliber, 
and  the  employment  of  shells  instead  of  bullets, 
brings  a  new  factor  of  dominant  importance  in 
aerial  combat.     Whereas  a  bullet  must  hit  one 


of  the  vulnerable  parts  of  the  aeroplane  to  do 
serious  damage,  a  shell  will  wreck  the  aeroplane 
practically  every  time  it  makes  a  hit. 

Formation  in  Air  Fighting 

Formation  in  air  fighting  is  part  of  the  latest 
developments  in  the  aerial  part  of  the  war. 
Fighting  in  formation  began  in  the  early  part 
of  1916,  and  by  the  spring  of  1917,  in  the  in- 
tensive air  fighting  that  preceded  the  Allies' 
drives,  aerial  combats  had  taken  place  in  which 
as  many  as  forty  aeroplanes  participated  on 
each  side. 

Since  then  the  ofiicial  reports  contain  many 
incidents  such  as  the  following,  which  was  dated 
June  6, 1917: 

"Five  hostile  formations,  all  of  which  consisted 
of  over  thirty  machines,  were  attacked  and  dis- 
persed with  heavy  casualties.  In  the  course  of 
the  fighting,  nine  German  aeroplanes  were 
brought  down  and  at  least  nine  others  were 
driven  down,  out  of  control.  Six  of  our  aero- 
planes  are  missing." 

There  are  many  instances  of  individual  avia- 
tors who  fought  from  4  to  10  enemy  aeroplanes 
and  came  out  victorious,  although  not,  of  course, 
bringing  down  the  10  machines. 


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Launp  Signals  for  Use  of  Leaders  of 
Formations 

The  code  letters  are  painted  on  the  machine 
where  visible  to  the  observer  and  within  reach 
of  the  pilot's  hand.  When  the  leader  wishes 
to  give  an  order,  he  places  his  finger  on  the 
letter  required,  which  the  observ^er  then  sends 
to  the  machines  concerned  with  the  lamp.  The 
order  can  be  acknowledged  by  the  lamp  or  by 
a  "waggle"  of  the  machine  if  lamps  are  not  car- 
ried. Single-seaters  working  with  two-seaters 
can  take  such  messages. 

The  principles  of  formation  defined  by  the 
British  General  Staff  (see  chapter  on  "War- 
planes  for  Bombing  and  Torpedo-Launching") 
are  applicable  to  fighting  patrols,  as  well  as  to 
bombing,  reconaissance,  and  other  patrols. 
The  British  General  Staff  also  points  out  that 
in  the  face  of  opposition  of  any  strength  offen- 
sive patrols  usually  have  to  fly  in  formation, 
in  order  to  obtain  the  advantage  of  mutual  sup- 
port, but  the  formation  adopted  may  be  gov- 
erned solely  by  the  requirements  of  offensive 
fighting.    Single-seater  scout  machines,  or  even 


A  \'ickers  gun  mounted  on  the  "Spad"  of  a  menilier  nf  the 
Lafayette  Flying  Corps,  and  the  belt  with  which  it  is  fed. 

two-seaters,  if  superior  in  speed  and  chmbing 
ability  to  the  great  majority  of  the  enemy's 
machines,  may  be  able  to  patrol  very  success- 


Onc  of  Franre's  Short  Distance  Bombing  Machines. 


BATTLEPLANES  AND  AIRCRAFT  GUNS 


57 


A  squadron  of  German  speed  bi- 
planes of  the  Albatros  type,  painted  in 
variegated  colors. 


fully  alone  or  in  pairs,  taking  advantage  of  their 
power  of  manoeuvering  and  acting  largely  by 
surprise  attacks;  but  in  the  case  of  machines 
which  do  not  enjoy  any  marked  superiority, 
formation-flying  is  essential.  Fighting  in  the 
air,  however,  even  when  many  machines  are  in- 
volved on  each  side,  tends  to  resolve  itself  into 


German  silver- 


1 

o 

o 

o 

o 

o 

o 

ORDINARY       ARMOR        INCENDIARY    EXPLOSIVE 
PIERCING       TRACING 

German  ammunition. 


3WAY    GASOLINE 

VAtves 


MOTOR  SPEED 
INDICATOR, 


FIXED 

hAACHINE- 
GON 


STARTING 
MAGNETO 


.  MAGAZINE 

MAONETO       1  FOR    FILLED 

SWITCH     EMPTY  cAnTA.OOt  BELT 
DCLT 

Position  of  the  fixed  macliine  gun   in  the 
fuselage  (as  seen  by  the  pilot) 

Courtesy  of  Aerial  Age  Weekly 


a  number  of  more  or  less  independent  combats, 
and  accordingly  it  has  been  found  advisable  to 
organize  a  purely  fighting  formation. 

As  far  as  possible,  the  groups  should  be 
permanent  organizations,  in  order  that  the  pi- 
lots may  acquire  that  mutual  confidence  and 
knowledge  of  each  other's  tactics  and  methods, 
which  is  essential  for  successful  fighting.  It 
must  be  impressed  on  pilots  that  the  group  is 
the  fighting  unit,  and  not  the  individual. 

Normally,  a  formation  shoidd  consist  of  not 
more  than  three  groups,  and  if  greater  strength 
is  required  separate  formations  should  be  em- 
ployed, acting  independently,  but  in  such  a  way 
as  to  be  mutually  supporting. 


k,'f^.^J?V^'         «*L.- 

British  aviators   figuring  out  a  raid 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


The  DeHaviland  Scout  Bi- 
plane, one  of  the  more  recent 
British    pusher-type    scouts. 


Ik         ^3u 


A  fighting  formation  should  consist  of  ma- 
chines of  one  type,  but  single-  and  two-seater 
machines  can  be  combined  for  similar  perform- 
ance. A  suitable  flying  formation  with  groups 
of  three  machines  advances  in  column  groups, 
with  flank  machines  echeloned  slightly  back, 
the  whole  formation  being  in  vertical  echelon. 
The  rear  group  is  the  highest,  and  in  the  case 
of  a  mixed  formation  consists  of  two-seaters, 
w^ith  machines  of  equal  performance. 

Fast  single-seaters,  if  combined  with  two- 
seaters,  should  fly  above  them,  circling  so  as  to 
obtain  a  good  view  all  aroimd. 

In  the  case  of  groups  of  two  machines  a  sim- 
ilar flying  formation  is  in  line  of  groups,  the 
two  machines  of  each  group  flying  one  behind 
the  other,  the  rear  machine  at  a  higher  altitude. 
The  flank  groups  should  not  be  echeloned  back, 
as  in  this  position  thej'  will  be  unable  to  use 
the  center  group. 


The    BritUb    Vickers    pusher   biplane    equipped    with    100    h.p. 
motor.     It   mounts   a   gun    forward. 


Offensive  Fighting  Tactics 

Realizing  the  fact  that  fighting  tactics  vary 
with  the  type  of  machine,  and  with  the  powers 
and  favorite  methods  of  individual  pilots,  the 
military  authorities  of  the  warring  counti'ies 
have  not  issued  set  rules. 

Rules  of  Manoeuver 

Individual  skill  in  manoevering  favors  sur- 
prise. A  pilot  who  is  thoroughly  at  home  in  the 
air  can  place  his  machine  by  a  steep  dive,  a 
sharp  turn,  or  the  like,  in  an  unexpected  posi- 
tion on  the  enemj^'s  "blind"  side,  or  under  his 
tail.  Individual  and  collective  power  of  manoeu- 
vering  is  essential  if  flying  in  formation  is  to 
be  successful,  or  even  possible.  It  can  only  be 
obtained  by  constant  practice. 

The  following  points  must  always  be  borne 
in  mind: 

( 1 )  Pilots  and  observers  must  know  the  fuel 
capacity  of  their  machine,  and  its  speed  at  all 
heights. 

(2)  The  direction  and  strength  of 
tlie  wind  must  be  studied  before  leav- 
ing the  ground  and  during  the  flight. 
This  study  is  most  important,  since 
wind  limits  the  range  of  action,  and 
machines,  when  fighting,  are  bound  to 
drift  down  wind. 

(3)  To  guard  against  surprise,  di- 
rection must  be  varied  fretjucntly,  un- 
less making  for  a  definite  i)oint,  and  a 
good  lookout  must  be  always  kept  in 
everv  direction. 


Gnome 


BATTLEPLANES  AND  AIRCRAFT  GUNS 


59 


''^'^WIJS^..  <■?'/?■":'';"■'',  '"^^'^.^f^-'T-    '  " 


BOMB 
RELEASED 


The  fusclagt'  of  cine  df  tlie  Gotha  biplanes  which  bombed  London.     Illustration  by  courtesy  of  Illustrated  London  News. 


(4)  Every  advantage  must  be  taken  of  the 
natural  conditions,  such  as  clouds,  sun,  and 
haze,  in  order  to  achieve  surprise. 

(5)  The  types  of  host"le  aeroplanes  must  be 
carefully  studied,  so  that  the  performance  and 
tactics  of  each,  its  blind  side,  and  the  best  way 
to  attack  it,  can  be  worked  out.  Some  machines 
have  a  machine-gun  mounted  to  fire  downward 


and  backward  through  the  bottom  of  the  fuse- 
lage. 

(6)  Height  means  speed;  since  it  is  easier 
to  overhaul  a  hostile  machine  on  a  dive.  If  a 
hostile  machine  seeks  safety  by  diving,  it  is 
bound  to  flatten  out  eventually  and  may,  there- 
fore, be  overtaken  by  a  machine  from  above, 
if  the  latter  dives  in  front  of  it.     The  hostile 


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One  of  the  German  Parabellum  aeroplane  guns. 


Three  quarter  view  of  tlie  Sopwitli  biplane. 


machine  must  be  watched  all  the  time,  in  case 
it  turns. 

(7)  The  engine  must  be  always  kept  well 
in  hand  in  a  dive.  If  it  is  allowed  to  choke,  the 
opportimity  will  be  lost. 


Thorough  Knowledge  of  Weapons 
is  Required 

Machine-guns  in  the  air,  as  on  the  ground, 
are  very  powerful  weapons  of  offense,  owing 
to  the  volume  of  fire  they  are  capable  of  pro- 


An  aerotlnmie  just  back  of  a  line  of  trenches  In  France  photof;ru))lietl   from   an    aeroplane.      A    twin-motored    ("luidron   and   some 
SupwiUiK  are  shown  on  the  ground.     The  motor  transports  arc  in  the  court-lilie  place.     (French  official  plioto.) 


BATTLEPLANES  AND     AIRCRAFT  GUNS 


«1 


A  French  type  of  biplane  used  for  aerial  photography  and  to  direct  artillery  fire,  showing  the  gun  mounting 
at  the  rear  seat.     (Photo  Committee  on  Public  Information.) 


UWIS  AUTOMATIC  MACHINC  GUN 
•  ..       jnODCiLi  ISIS       ... 


Section  diagrams  ot  the  Lewis  Automatic  Machine  Gun.  The  gun  is  an  air-cooled  gas-operated,  magazine-fed  arm,  weighing 
26  pounds.  Its  speed  and  ability  to  function  automatically  in  any  position  are  due  to  the  use  of  detachable  drum-shape  rotating 
magazines  holding  from  47  to  97  cartridges.  It  may  be  used  with  tripods  or  mountings  of  any  design.  The  Lewis  gun  has 
shown  adversility  and   sureness   of  action  which  makes  it  equally   effective  on  rigid   bases  or  the  undulating,  fragil  supports  in 

the  air. 


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ducing.  Their  effective  use  in  the  air  demands 
even  more  skill  and  practice  than  on  the  ground. 
It  is  dependent  on: 

(1)  Absokite  famiharity  with  the  mechan- 
ism of  the  gun,  so  that  the  jamming  can  be 
rectified  in  the  air. 


(2)  A  high  degree  of  skill  in  manipulation 
and  accuracy  in  aim,  both  on  the  ground  and  in 
flight. 

(3)  Constant  study  of  the  conditions  affect- 
ing their  use  in  an  aeroplane,  and  continual 
practice  under  these  conditions. 


Memoranda: 


I 


CHAPTER  V 

THE  FUNDAMENTAL  PRINCIPLES  OF  AERIAL  COMBAT 

By  Oscar  Ribel 
Chief  Instructor  in  One  of  the  French  Military  Flying  Schools 
Translation  by  Augustus  Post 


The  fifth  arm  has  taken  a  very  important 
part  in  the  European  war.  The  warmest  ad- 
vocates of  mihtary  aviation  in  times  of  peace 
never  dreamed  of  the  vital  importance  of  the 
aeroplane  to-day. 

In  1907  the  most  remarkable  aerial  flights 
were  no  farther  than  1  kilometer,  or  %ths  of  a 
mile,  at  a  height  of  30  meters,  about  100  feet. 
The  marvelous  accomplishments  in  aviation 
during  the  last  ten  j^ears  are  astounding.  The 
most  optimistic  prophecies  did  not  anticipate 
one  half  the  actual  reality.  Who  dared  to  be- 
heve,  when  Farman  timidly  tried  his  wings  at 
Issy-les-JNIoulineaux,  that  nine  years  later  es- 
cadrilles  of  thirty  or  forty  aerial  warriors  would 
sail  off  into  space  to  engage  in  heroic  aerial 
combat  against  each  other. 

Aerial  fighting  has  given  an  opportunity  to 
develop  in  both  the  French  and  English  rare 
qualities  of  courage,  coolness,  and  hardihood. 
The  Germans,  on  the  other  hand,  are  less  well 
trained  and  equipped  than  their  adversaries  but, 
as  is  frequently  recorded,  exhibit  undeniable 
bravery.  The  system  used  in  aerial  fighting 
differs  in  the  German  and  Allied  forces.  In 
France  we  have  distinct  types  of  aeroplanes  for 
different  purposes,  that  is  to  say,  for  recon- 
noitering,  "spotting"  or  directing  artillery  fire, 
and  for  carrying  bombs.  All  these  aeroplanes 
are  protected  by  an  escort  of  machines  espe- 
cially adapted  for  speed  and  fighting,  and  they 
are  well  armed.  The  Germans  use  their  ma- 
chines more  indiscriminately  for  these  various 
military  operations.  They  do  not  have  so 
many  types  of  machines,  and  thus  those  they 
have  are  capable  of  being  used  for  different 


purposes  with  equal  efficiency.  An  exception 
to  this  statement  are  the  Fokkers  and  the  Wal- 
vets,  which  are  flown  by  their  most  expert  avi- 
ators and  are  used  exclusively  for  fighting  the 
enemj'. 

From  a  technical  point  of  view  French  avia- 
tion is  about  the  same  as  German,  but  our  pilots 
are  superior  scientifically  to  the  Germans,  and 
the  number  of  cur  "aces"  is  constantly  increas- 
ing. Practically  all  of  them  fly  the  Nieuport 
or  Spad,  and  their  victories  up  to  date  can  be 
numbered  by  the  himdred.  Naturally  we  can- 
not describe  the  methods  employed  by  each  one 


63 


Fig.  1 — The  "Loop"  as  an  aerial  military  manoeuver.  At- 
tacked by  four  or  five  German  machines,  a  French  biplane 
turned  completely  over  and  returned  by  means  of  "looping  the 
loop"  to  attack  the  squadron  which  was  attacking  him  in  the 
rear. 

of  these  "aces"  in  fighting  the  enemy,  because 
almost  every  one  depends  upon  the  marvelous 
individual  skill  with  which  they  perform  their 
acrobatic   feats.     One   example   among  thou- 


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sands  may  be  quoted.  It  is  well  known  among 
escadrilles  at  the  front  and  will  give  an  idea  of 
how  every  pilot  must  cut  the  "Gordian  Knot." 
In  the  course  of  a  reconnoitering  flight  in  the 
East,  sub-Lieut.  Navarre  found  himself  sur- 
rounded by  five  or  six  German  machines. 
Three  or  four  were  above  him  and  the  others 


^ 


t 
I 

ill 


Ol 


B 


ZOOmetres, 


Fig.  2 — The  favorite  attack  of  the  Walvets.  Walvets  patrol 
two  by  two.  A  200  meters  above  and  200  meters  behind  B.  If 
a  machine  C  is  encountered  B  engages  in  combat  with  it  while 
A  remains  to  survey  the  zone  of  battle  to  prevent  surprise  on 
the  part  of  another  machine  which  might  come  up  to  render 
assistance. 


were  below  or  at  the  sides,  which  prevented  him 
from  going  to  the  right  or  to  the  left,  either 
in  rising  or  descending.  It  seemed  impossible 
for  him  to  escape.  Without  losing  for  an  in- 
stant his  remarkable  coolness,  our  valiant  "ace" 
surprised  his  adversaries  by  making  a  complete 
loop  over  the  entire  group  of  assailants,  and 
following  up  the  nearest  machines,  discharged 
an  entire  belt  of  cartridges  from  his  machine 
gun  and  brought  down  two  machines  one  after 
the  other.  The  other  pilots  retreated  as  fast 
as  possible  to  their  lines,  pursued  by  the  in- 
trepid Navarre. 

The  German  "aces"  are  much  less  numerous 
than  our  own,  the  best  among  them  being  Cap- 
tain Boelke,  who  died  the  28th  of  October,  1916, 
after  having  brought  down  his  fortieth  adver- 
sary. 

We  count  as  victories  for  our  pilots  only  the 
enemy  machines  which  fall  inside  our  lines,  or 
fall  in  flames  in  unoccupied  territory',  but  the 
Germans  do  not  hesitate  to  count  every  machine 


which  is  brought  down  for  one  cause  or  another, 
and  is  thus  obliged  to  abandon  the  fight.  If 
we  adopted  the  same  method  of  counting,  it 
is  certain  that  Guynemer,  among  others,  has 
brought  down  more  than  sixty  enemy  machines. 

French  aviators  often  fight  twenty  or  thirty 
kilometers  behind  the  German  front.  A  Ger- 
man reconnoitering  party  must  be  checked  in 
its  operations  and  brought  down  if  possible. 
During  the  course  of  our  ofi'ensive  on  the 
Somme  and  at  Verdun,  our  machines  estab- 
lished a  veritable  barrier  across  our  front, 
through  which  no  German  aviator  was  able  to 
penetrate;  and  this  lasted  for  several  days. 

Speed  and  climbing  ability  are  essential  for 
a  fighting  machine,  as  the  aviator  has  to  outfly 
his  adversary  and  strike  him  in  a  vital  spot  at 
an  opportune  moment.  The  Fokkers,  the 
Walvets,  and  the  L.V.G.  are  the  principle 
types  used  for  reconnoitering  over  the  front, 
and  have  a  speed  of  1.50  kilometers  per  hour 
(about  100  miles).  They  climb  very  rapidly, 
and  the  altitiade  at  which  aerial  combat  is  gen- 
erally fought  is  about  4000  meters  (14,000 
feet). 

Generally  speaking,  the  German  fighting 
pilots,  especially  those  who  fly  the  Walvets, 
employ  the  following  tactics  when  they  come 
over  our  lines  and  engage  our  aviators.  They 
always  go  in  groups  composed  of  units  of  two 
machines  each.  If  an  enemy  machine  is  en- 
gaged by  one  of  these  units,  the  first  of  the  Ger- 
man aviators  begins  the  battle  and  the  second 
man  remains  about  two  hundred  meters  above, 
his  mission  being  to  overlook  the  zone  of  combat 
without  interfering  directly  with  the  fighting. 
If  a  second  adversary  comes  to  the  rescue,  how- 
ever, it  is  his  turn  to  attack  and  drive  away 
the  rescuer,  while  if  his  partner  is  vanquished, 
he  returns  to  his  lines  as  quickly  as  possible. 
Often  the  manoeuvers  are  more  involved,  and 
the  aviators  fly  in  large  squadrons  for  mutual 
protection.  If  an  isolated  enemy  is  encoun- 
tered, he  is  quickly  surrounded  and  must  seek 
safety  in  the  speed  of  his  flight. 

The  speed  of  the  fighting  machines  is  great, 
and  there  is  danger  therefore  of  breaking  the 
wings.  A  machine  which  flys  at  180  kilometers 
an  hour  (about  110  miles),  rises  two  thousand 


FUNDAMENTAL  PRINCIPLES  OF  AERIAL  COMBAT 


65 


meters  in  seven  minutes  (about  7000  feet),  and 
dives  almost  vertically  from  this  height,  ex- 
periences a  tremendous  strain  which,  in  time, 
is  apt  to  cause  weakness.  Fighting  machines 
have  to  perform  extraordinary  feats  in  pur- 
suing the  enemy.  They  dive  vertically,  and  if 
the  wings  break  under  the  jiressure  caused  by 
these  conditions,  the  machine  at  once  falls. 
German  machines,  generally  speaking,  have  a 
good  factor  of  safety  in  their  different  parts. 
Many  accidents  have  been  caused  after  a  ma- 
chine has  had  many  repairs,  or  through  some 


Fig.  3 — The  "Dive  Attack."  To  train  the  machine  gun  upon 
its  target  below  the  machine  must  be  pointed  down  at  least  60 
degrees. 


hidden  fault  of  constniction.  Recently  at  the 
front  near  Verdun  an  aviator  was  pursuing  a 
German  machine  and,  in  his  turn,  was  pursued 
by  a  small  Rumpler  biplane.  At  the  moment 
when  the  French  pilot,  after  bringing  down  his 
first  adversary,  was  preparing  to  face  this  new 
assailant,  the  Rumpler  dived  straight  toward 
the  earth  in  a  sudden  bold  dash.  The  wings 
broke  and  folded  up  above  the  fuselage.  Many 
Rumpler  machines  have  met  the  same  fate  in 
other  air  battles.     The  constructors  thus  invol- 


untarily contribute  to  the  success  of  our  pilots, 
and  thereby  deserve  our  thanks. 

The  German  "aces"  generally  fight  in  con- 
junction with  a  squadron  of  accompanying  ma- 
chines. These  are  charged  with  the  duty  of 
occupying  the  attention  of  the  enemy  until  an 
opportune  moment  for  attack.  Boelke  adopted 
the  following  tactics,  as  described  by  M. 
Jacques  Mortane.  The  German  flew  with  an 
escadrille  of  five  or  six  good  pilots  on  Rolands, 
Walvets,  or  Fokkers;  he  preferred  a  Fokker, 
but  sometimes  was  seen  on  a  Roland,  or  a  small 
Aviatik.  As  soon  as  the  well-known  profile 
of  an  Allied  machine  was  seen  on  the  horizon, 
the  squadron  rose  to  engage  it.  The  duty  of 
Boelke's  support  was  to  surround  the  enemy 
and  block  his  path.  They  would  fire  from  all 
sides,  suddenly  ceasing  the  instant  Boelke  made 
his  entrance  upon  the  scene.  The  latter  would 
dash  at  his  prey  and  attack  furiously,  firing  a 
thousand  cartridges  from  his  machine  gun. 
Boelke  followed  up  the  fight,  in  contrast  to  the 


Fig.  4 — The  tactics  of  the  famous  Boelke.  The  duty  of  the 
machines  C,  D,  E,  is  to  surround  their  adversary  B  at  a  given 
moment.  A,  who  has  been  hidden  from  the  view  of  his  adversary, 
dashes  at  him,  firing  his  machine  gun  furiously. 

custom  of  many  of  his  compatriots.  These 
rarely  continued  an  engagement  with  an  ad- 
versary who  was  not  brought  down  at  the  first 
shot.  Such  was  the  method  adopted  by  Lieut. 
Immelmann,  one  of  the  best  of  the  German 
aviators.     He  would  dash  up  to  an  enemy's 


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machine,  and  when  so  close  that  a  collision 
seemed  imminent,  would  discharge  his  machine 
gun  at  it  as  he  passed  by.  Once  out  of  range 
he  would  not  return  to  the  attack,  but  would 
fly  away,  which  cannot  be  considered  very 
heroic. 

The  Germans  usually  fly  very  high.  When 
they  see  French  machines  they  hesitate  to  cross 
our  lines,  which  are  always  well  guarded  by  our 
fighting  machines,  especially  during  the  periods 
of  Allied  drives.  The  weather  plays  an  im- 
portant role  in  air  fighting.  Calm  days,  when 
the  sky  is  full  of  dark,  gray  clouds,  are  the 
most  favorable  for  surprise  attacks.  The 
clouds  act  as  a  screen  and  allow  the  aviator  to 
hide  until  the  last  moment,  before  he  makes  a 
dash  at  an  unsuspecting  enemy. 

The  Germans  are  ■  well  versed  in  one  trick 
which  they  invented  and  which  they  have  often 
used.  When  the  bank  of  clouds  is  thick,  one 
of  their  machines  flies  down  to  an  altitude  of 
two  or  three  hundred  feet.  This  machine  may 
be  of  any  class,  but  it  is  usually  a  slow  machine 
of  an  old  type,  and  not  heavily  armed. 


Fig.  5 — The  Tactics  of  IiiiiiicliiKin.  The  iiiiuliino  A  daslies 
straiglit  at  its  enemy  B,  firing  at  him  furiously.  If  he  failed  to 
bring  down  his  prey  he  fled  and  did  not  return  to  the  charge. 

It  appears  to  be  relatively  easy  prey,  and  is 
quickly  discovered  by  the  French  machines. 
They  give  chase,  not  hesitating  to  follow  it, 


even  to  some  distance  behind  the  German  lines. 
At  the  moment  when  the  French  pilot  finds 
conditions  most  favorable  to  begin  his  attack, 
three  or  four  German  fighting  machines  of  the 
latest  and  most  formidable  model  appear. 
Flj'ing  above  the  clouds,  they  have  been  follow- 
ing the  two  antagonists  while  hidden  from  view, 
and  never  appear  until  the  enemy  is  at  least 
twenty  or  thirty  kilometers  from  his  base.  The 
number  of  attacking  machines,  and  the  difficul- 
ties in  getting  help  in  time,  make  it  an  extremely 
precarious  predicament  for  the  French  avia- 
tor. 

An  air  battle  does  not  necessarily  end  by 
the  complete  destruction  of  an  enemy  machine, 
or  the  killing  or  disabling  of  a  pilot.  A  case 
has  occurred  where  a  German  aviator  was  at- 
tacked by  a  French  "ace."  The  German  was 
convinced  that  he  had  no  chance,  lost  his  nerve, 
and  preferred  to  come  down  in  safety  to  having 
his  body  riddled  with  bullets.  He  directed  the 
observer  with  him  to  throw  up  his  hands,  while 
he  steered  his  captured  machine,  and  following 
his  vanquisher  to  the  nearest  aviation  field, 
landed  by  the  side  of  his  captor.  In  this  way 
Lieut.  Laffon  gathered  out  of  a  clear  sky  a 
Fokker  of  the  latest  model,  and  brought  it  to 
the  aviation  center  of  Plessis-Belleville.  The 
feat  was  all  the  more  remarkable  and  creditable 
to  the  officer  because  he  had  no  arms  aboard, 
except  a  revolver. 

Before  the  war  the  question  of  arming  ma- 
chines received  only  superficial  study,  at  least 
in  France.  At  the  beginning  of  hostilities  only 
a  few  aeroplanes  were  equipped  with  machine 
guns.  ]Many  of  the  aviators  had  only  a  rifle 
with  which  to  defend  themselves  against  attack. 
To-day,  as  the  enemy  well  knows,  our  machines 
are  very  efficiently  armed  for  both  attack  and 
defense.  The  position  of  a  machine  gun  on  the 
aeroplane  plays  a  great  part  in  the  success  of 
air  fighting.  We  know  that  the  Germans  have 
studied  the  problem  with  great  care,  and  their 
machine  guns  are  mounted  in  one  of  the  five 
following  positions: 

(1)  Above  the  upper  plane  (machine  guns 
stationarjs  firing  through  the  propeller). 

(2)  Along  the  fuselage  (gun  stationary, 
shooting  through  the  propeller). 


FUNDAMENTAL  PRINCIPLES  OF  AERIAL  COMBAT 


67 


(3)  In  rear  of  the  lower  plane  (guns  mova- 
ble in  a  revolving  turret) . 

(4)  In  front  of  the  cockpit  (gun  movable 
and  able  to  fire  in  all  directions ;  single-motored 
machine  with  a  pusher  propeller). 

(5)  Both  in  front  and  in  rear  of  the  cockpit 
(gun  movable;  twin-motored  machine,  tractor 
propellers,  with  a  central  cockpit). 

The  first  arrangement  has  been  adopted  by 
several  manufacturers  of  small  speedy  bi-planes 
in  Germany,  and  is  similar  in  almost  all  points 
to  the  system  used  on  our  Nieuports.  The  ma- 
chine gun  is  stationary  on  the  upper  plane,  par- 
allel with  the  fuselage,  and  is  controlled  by  a 
"Bowden"  flexible  wire  control  fastened  to  a 
rod  beside  the  pilot.  To  train  the  gun  upon 
its  mark  in  the  vertical  plane  one  must  point 
the  aeroplane  up  or  down;  and  to  aim  in  the 
longitudinal  plane,  the  aeroplane  must  be 
pointed  in  the  direction  of  fire,  since  the  gun 
is  firmly  mounted  on  the  axis  of  the  nlachine. 
When  the  aeroplane  attacked  is  just  below  the 
pursuing  machine,  the  latter  must  dive  verti- 
cally and  attack  its  adversary  while  inclined  at 
ninety  degrees,  in  order  to  bring  the  machine 
gun  into  range.  In  practice,  the  angle  of  at- 
tack is  not  quite  as  steep  as  this,  for  the  attacked 
machine  is  not  exactly  beneath  its  adversary's 
gun.  It  is  at  least  100  meters  (300  feet)  away, 
and  when  the  attacking  machine  opens  fire,  it 


angle.  The  difficulty  of  hitting  the  mark  is 
great,  since  the  gunner  and  his  object  are  mov- 
ing rapidly,  and  the  movements  in  steering  an 
aeroplane  are  complex  and  relatively  slow. 
The  mounting  of  the  gun  on  the  upper  plane 
is  best  adapted  to  the  machine  which  has  the 


Mitrailleuse  fine 


-Mitrailleuse  mobile 
a  tourelle 


Fig.  6 — Mounting  of  the  two  machine  guns  on  the  new  bi- 
plane L.  G.  V.  The  machine  gun  in  front  shoots  through  the 
propeller  and  is  fired  by  the  pilot.  The  rear  gun  mounted  in  a 
revolving  turret  is  fired  by  the  observer. 

is  at  an  angle  of  55  or  65  degrees.     This,  when 
compared  with  the  horizontal,  is  a  considerable 


Fig.  7 — Arrangement  of  a  machine  gun  with  a  limited  field 
of  fire.  The  gun  is  mounted  in  front  of  the  car  on  an  elevated 
support.  The  field  is  limited  by  the  extremities  of  the  aero- 
plane. 

pilot's  seat  behind  the  wings.  Consequently, 
to  gain  the  best  chance  to  reach  the  aviator  him- 
self, his  adversary  must  strive  to  attack  from 
above. 

The  mounting  of  guns  for  firing  through  the 
propeller  was  first  attempted  by  Roland  Gar- 
ros, who  was  taken  prisoner  before  he  was  able 
to  destroy  his  machine.  The  Germans  were 
quick  to  copy  this  method  of  mounting  guns, 
and  have  made  many  improvements,  as  it  was 
well  adapted  to  the  Fokker  machine  and  gave 
very  good  results.  On  the  Fokkers,  the  gun  is 
mounted  stationary  above  the  hood,  a  little  to 
the  right  of  the  axis,  on  a  level  with  the  head  of 
the  pilot.  The  propeller  causes  only  slight  in- 
convenience, but  on  account  of  the  gun  being 
firmly  fixed,  the  entire  machine  must  be  aimed, 
with  the  attendant  difficulties  already  men- 
tioned. It  is  also  possible  to  shoot  through  the 
propeller  by  using  an  automatic  device  to 
momentarily  stop  the  fire  during  the  passage 
of  the  propeller-blade  in  front  of  the  gun.  The 
latter  is  mounted  directly  behind  the  propeller. 
In  this  device  the  motor  is  connected  with  the 
machine  gun,  and  a  cam  controls  a  mechanism 


68 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


which  stops  the  fire  for  /^oo  of  a  second,  while 
the  blades  of  the  propeller  are  in  the  path  of 
the  bullets.  When  the  propeller  has  passed, 
the  gun  is  free  to  fire  again.  If  a  pilot  wishes 
to  shoot,  he  presses  a  small  lever  placed  on 
the  steering  post,  which  is  connected  to  the 
trigger  of  the  gun. 

The  company  licensed  to  make  the  Nieuports 


Fig.  8 — Vertical  field  of  a  machine  gun  mounted  on  a  pivot. 
In  the  vertical  plane  the  fire  is  very  extended.  It  is  only  lim- 
ited by  the  parts  of  the  aeroplane. 

in  Italy  recently  invented  a  device  which  en- 
ables one  to  shoot  through  the  propeller,  prac- 
tically identical  with  that  used  on  the  Fokker. 
It  is  based  on  the  difference  between  the  speed 
of  the  gun  and  the  speed  of  the  propeller ;  that 
is  to  say,  the  ratio  between  the  bullet  and  the 
propeller-blade  is  700  to  160.  This  difference 
is  used  to  regulate  the  stopping  of  the  machine 
gun  during  the  passage  of  the  blade  of  the  pro- 
peller in  front  of  the  barrel  of  the  gun. 

The  arrangement  which  Garros  used  was  ex- 
tremely crude.  It  consisted  simply  of  a  small 
piece  of  steel,  hard  enough  to  resist  a  bullet, 
placed  on  each  blade  of  the  propeller  opposite 
the  barrel  of  the  gun.  If  a  bullet  chanced  to 
hit  the  propeller,  the  metal  deflected  it  without 
causing  damage  to  the  propeller-blade. 

The  German  bi-planes,  like  the  Ij.  V.  G.,  for 
example,  have  two  machine  gims.  One  is  sta- 
tionary on  the  upper  plane,  the  other  movable 


and  mounted  on  the  fuselage  behind  the  observ- 
er's seat,  on  a  revolving  turret.  This  gives  it  a 
great  range  of  fire.  The  turret  is  a  ring  of 
wood  which  turns  freely  around  the  cock-pit 
on  ball-bearings,  with  a  bracket  arm  which  holds 
the  gun  and  permits  it  both  to  be  trained  in 
the  vertical  plane  and  swung  around  in  the  hori- 
zontal plane  to  either  side  of  the  fuselage,  so  as 
to  point  in  any  direction.  Two  small  clamps 
hold  the  turret  and  gun  firmly  in  any  position. 
This  arrangement  gives  a  wide  range  or  fire  to- 
ward the  rear  in  all  directions,  and  on  either 
side,  both  above  and  below.  It  is  even  possible 
to  fire  ahead,  above  the  wings  of  the  machine. 
The  rear  machine  gun  is  often  replaced  by  a 
"fusil  mitrailleuse,"  or  automatic  rifle.  To  pro- 
tect the  blank  sector  of  this  gun  arrangement, 
the  fuselage  is  provided  with  a  tube-like  open- 
ing, inclined  at  an  angle  of  forty-five  degrees. 
This  tube  allows  the  gunner  to  see  and  fire 
through  the  fuselage  at  the  enemy,  if  he  tries  to 
hide  from  view  of  the  gunner  below  the  rear  of 
the  machine. 

The  machine  guns,  when  mounted  in  front 
and  rear,  are  both  fired  by  the  observer,  but  in  a 
recent  type  the  forward  gim  was  placed  be- 
tween the  two  planes  beside  the  motor  and 
parallel  to  it,  being  fired  by  the  pilot. 

At  the  beginning  of  the  war  some  German 
machines  had  a  cockpit,  like  the  French  Far- 
mans,  with  a  gun  mounted  on  an  elevated  sup- 
port. This  mounting  left  a  large  blank  sector 
of  fire,  and  was  afterward  abandoned.  The 
gun  did  not  have  much  sweep,  and  its  zone  of 
fire  was  restricted  by  passengers,  wings,  pro- 
peller, cables,  struts,  etc.  This  was  remedied 
in  a  measure  by  mounting  it  on  a  turret,  which 
allowed  it  to  fire  in  all  directions,  but  not  at  all 
angles.  This  type  of  machine  is  not  used  to- 
day at  the  front.  It  has  been  replaced  by  the 
A.  G.  O.,  which  is  provided  with  two  motors  and 
tractor  propellers,  and  a  central  car  armed  with 
two  machine-gun  turrets.  One  machine  gun  is 
placed  forward,  sweeping  the  horizon  for  180 
degrees  and  the  other  is  in  the  rear,  its  range 
also  controlling  180  degrees  of  the  horizon. 
Between  them  the  entire  horizon  is  covered. 
All  of  the  German  machines  are  armed  with  one 
or  two  Maxims,  Lewis,  or  Parabcllum  machine 


FUNDAMENTAL  PRINCIPLES  OF  AERIAL  COMBAT 


69 


guns.  Some  aeroplanes  have  three  machine 
guns,  and  these  are  considered  the  best  for  ac- 
tual service.  The  Parabellum  has  a  belt  of 
cartridges  which  contains  not  less  than  a  thou- 
sand projectiles. 

If  each  pilot  has  his  own  method  of  fighting, 
each  type  of  machine  has  its  weak  points;  and 
these  points  must  be  well  known,  in  order  to 
make  a  successful  attack  upon  it.  When  at- 
tacking a  machine  it  is  necessary  to  learn  how 
its  guns  are  mounted,  in  order  to  know  whether 
to  attack  it  from  above,  below,  or  from  the  side. 
If  the  field  of  fire  of  the  machine  gun  has  cer- 
tain dead  points,  it  is  thereby  handicapped,  and 
may  be  attacked  to  advantage.  A  pilot  who  is 
attacked  by  an  Aviatik  is  exposed  to  fire  from 
all  directions,  except  in  the  zone  in  front  of  the 
propeller.  In  the  case  of  ordinary  Aviatiks, 
with  the  gunner  in  front,  the  machine  gun  can 
be  placed  at  will  on  the  right  or  left  side  of  the 
fuselage.  It  is  placed  upon  a  pivot  mounted 
on  a  carriage.  This  carriage  can  be  moved  on 
two  guides,  or  slide  bars,  that  run  along  the 
fuselage  to  a  convenient  point  for  firing.  A 
clamp  holds  the  carriage  at  any  spot,  so  that 
one  can  fire  in  all  directions.  An  aviator  who 
attacks  an  L.  V.  G.  which,  as  we  have  explained, 
has  two  machine  guns,  must  decide  whether  it 
is  better  to  stay  in  front  or  in  the  rear  of  the 


line  of  fire  between  the  forward  and  the  rear 
gun. 

Thus  we  see  that  the  identification  of  the  type 
of  enemy  aeroplane  is  absolutely  necessary  for 


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Fig.  9 — Mounting  of  two  machine  guns  in  a  bi-motored  ma- 
chine. The  arcs  of  fire  in  the  horizontal  plane  meet  each  other 
when  the  guns  are  mounted  in  this  manner. 

an  air  warrior.  Unfortunately,  the  diversity  of 
types  of  machines  employed  by  the  Germans, 
and  the  frequent  changes  made  in  service,  ren- 
ders this  identification  extremely  difficult. 


German  positions  reduced 
by  Frencli  artillery  through 
the  directions  given  by  aero 
observers.  The  center  pho- 
tograph shows  the  trenches 
and  German  position  in 
broad  perspective.  The  im- 
portant positions  are  shown 
by  numbers  and  are  shown 
in  detail  in  the  smaller  pho- 
tographs. The  aero  observ- 
ers directed  the  artillery 
fire  on  these  positions. 


Photograph  No.  1  shows  the 
effects  of  the  French  shells 
on  a  typical  one  of  many 
German  points  d'appui.  No.  2 
shows  the  condition  in  which 
the  captured  German  trenches 
were  found.  No.  3  shows  the 
remains  of  the  emplacement  of 
a  German  battery.  No.  4 
shows  the  ruins  of  a  small  l)ut 
very  strong  German  fortified 
post.  No.  6  shows  the  result 
of  the  French  bombardment  on 
the  German  defensive  line  be- 
fore the  River  Suiiipe.  No.  (!, 
like  No.  2,  is  another  typical 
scene  in  the  captured  Germnn 
trenches,  showing  their  general 
appearance  after  the  bombard- 
ment. No.  7  shows  all  that  re- 
ma  ine<l  of  some  of  the  deepest 
German  dug-outs  and  trench 
shelters.  No.  8  illustrates  the 
demolishing  effect  of  the  French 
artillery  fire  on  the  solid  con- 
crete structures  built  by  the 
Gennans    in    their    trenches. 

70 


An  aero  observer  flying  over  the  German  lines  in  a  Farman   biplane.    The   shrapnel   is    bursting   around  him. 


CHAPTER  VI 

DIRECTING  ARTILLERY  FIRE  BY  NIGHT  AND  DAY  SIGNALING  TO 

AND  FROM  AIRCRAFT 


Aircraft  are  the  necessary  adjunct  of  coast 
and  field  artillery,  and  the  aero  observer  is  the 
man  behind  the  man  behind  the  gun.  Thou- 
sands of  American  aero  observers  will  have  to 
be  trained,  therefore  the  information  is  given  as 
complete  as  possible,  so  that  prospective  observ- 
ers may  familiarize  themselves  with  the  funda- 
mental principles. 

Aeroplanes  and  captive  balloons  are  used  for 
spotting  artillery  fire. 

The  observers  have  to  perform  two  functions, 
mainly  as  follows : 

(1)  To  locate  the  target,  which  may  consist 
of  hostile  batteries,  bodies  of  troops,  advanced 
trenches,  trains  and  mechanical  transports 
bringing  supplies  or  reinforcements  to  the 
enemy,  temporary  headquarters,  or  strategic 
positions  held  by  the  enemy. 

(2)  Having  discovered  the  target,  the  ob- 
server directs  his  battery  to  open  fire,  and  then 
notifies  the  gunners  of  the  effect  of  the  fire  by 
wireless,  if  from  an  aeroplane,  and  telephone 
from  a  kite-balloon. 


71 


Practice  makes  it  possible  for  the  aviator  and 
the  gunners  to  reach  such  a  thorough  under- 
standing that  the  observer  need  not  send  more 
than  brief  wireless  signals,  such  as  "short," 
"long,"  "right,"  "left."  Likewise  the  gunner 
seldom  has  to  fire  more  than  three  shots  before 
hitting  the  target. 

The  observer  must  know  something  about 
artillery,  such  as  the  fact  that  field  guns  are 
used  for  barrage  fire  and  howitzers  for  counter 
battery  destruction. 

Wliile  looking  for  the  target  the  aviator  may 
have  to  fly  down  low.  As  soon  as  he  has  found 
the  target  he  flies  to  whatever  height  is  neces- 
sary to  avoid  crossing  the  trajector  of  the  shells. 

The  aviators  cooperating  with  the  artillery  are 
usually  located  at  an  aerodrome  located  from 
ten  to  fifteen  miles  behind  the  firing  Enes,  and 
are  instructed  to  be  over  a  given  place  at  a  cer- 
tain hour  to  spot  the  firing.  At  the  time  desig- 
nated the  aviators  hover  over  the  batteries  and 
watch  the  results  of  the  firing. 

From  a  height  of  4500  to  6000  feet  the  ob- 


72 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


servers  can  usually  see  clearly  the  effect  of  firing 
of  large  caliber  guns,  but  the  firing  of  three-inch 
guns  is  very  hard  to  detect. 

Well-trained  observers  are  necessary  for 
spotting,  as  it  is  easy  to  confuse  the  puffs  of 
smoke  of  the  hostile  anti-aircraft  guns  with  the 
puffs  of  smoke  of  the  shooting  of  one's  bat- 
teries. The  fact  that  the  enemy's  anti-aircraft 
guns  keep  up  a  sustained  fire  against  the  avia- 
tor, and  that  hostile  aei'oplanes  may  be  lurking 
in  the  sky  ready  to  plunge  down  on  the  unsus- 
pecting artillery  observer,  turning  on  him  a  rain 
of  bullets  from  two  or  more  Lewis  or  Vickers 
guns,  prevents  the  observer  from  giving  all  his 
attention  to  watching  the  result  of  the  fire  of  his 
batteries. 

The  observer  often  sees  what  appears  to  be  a 
hit  on  the  part  of  his  battery,  but  which  is, 
in  reality,  an  anti-aircraft  gun  shooting  at 
him. 

While  spotting  artillery  fire  the  aeroplanes 
usually  fly  in  figures  8s  and  circles,  changing 


their  direction  as  often  as  possible,  so  as  not  to 
allow  the  men  behind  the  anti-aircraft  guns  the 
chance  of  anticipating  what  direction  they  will 
fly  next — because  in  such  a  case  the  anti-air- 
craft guns  would  be  turned  effectively  on  the 
aeroplanes. 

While  the  work  of  spotting  artillery  fire  re- 
quires all  the  faculties  that  the  aviator  and  ob- 
server possess,  it  is  not  more  dangerous  than 
bombing  or  aerial  fighting.  For  one  thing,  the 
machine  is  usually  in  flying  distance  of  its  own 
aerodrome,  where  it  can  land  in  case  of  being 
badly  hit. 

This  last  remark  must  be  qualified,  because 
aeroplanes  engaged  in  spotting  artillery  fire  are 
always  hit  by  bullets  or  pieces  of  shrapnel. 

The  danger  from  the  aeroplane  catching  fire 
is  also  minimized  somewhat  by  the  fact  that  the 
aviator  is  in  flying  distance  of  the  aerodrome, 
although  the  only  safe  protection  from  fire  is: 

(1)  To  use  aeroplanes  the  wings  of  which 
are  varnished  with  an  inflammable  dope. 


Directing  ortlllrry  Arc  over  the  inountalnii.     Monte  Pasubio,  on  the  Trentlno  front,  as  seen  from  a  Capronl  macliiiii'. 


DIRECTING  ARTILERY  FIRE 


T8 


(2)  To  always  have  a  fire  extinguisher  at 
hand. 

(3)  Every  machine  of  this  type  should  have 
an  arrangement  which  permits  the  aviator,  as 
soon  as  he  is  within  gliding  distance  of  a  landing 
field,  or  sooner  if  necessary,  to  open  a  valve  and 
let  out  all  the  gasoline  and  oil. 

Some  remarkable  records  have  been  made  by 
aviators  and  observers  engaged  in  spotting 
artillery  fire.  Among  them  is  the  record 
of  the  French  lieutenant,  Perrin  de  Bricham- 
baut,  who  has  been  engaged  in  this  work  since 
the  beginning  of  the  war  and  in  less  than  two 
years  flew  over  the  enemy  lines  eleven  hun- 
dred hours.  The  record  for  one  day  was  seven 
hours  of  continuous  flying  over  the  enemy 
lines ! 

Spotting  artillery  fire  at  night  is  more  diffi- 
cult in  a  way,  but  less  dangerous — provided  the 
aviator  has  had  experience  in  night-flying.  The 
targets  are  detected  by  the  lights,  since  the 
enemy  cannot  operate  unless  it  has  lights,  and 
even  the  smallest  liglit  is  seen  from  the  air. 
The  flash  of  guns  being  fired  supphes  the  di- 
rections to  the  enemy  batteries.  At  night  both 
the  wireless  and  the  Very  pistols  are  used  for 
signaling. 


An  artillery  observer  flying  a  Caudron  biplane  over  the  German 
lines,  photographed  from  another  aeroplane. 


Methods  and  Codes  Used  for  Communi- 
cating From  and  To  Aircraft 

The  methods  and  codes  used  in  communi- 
cating from  and  to  aeroplanes  change  continu- 
ously, as  each  side  quickly  learns  the  enemy's 
methods  and  codes  and  any  improvements 
made.     But   there   are  basic   principles  which 


A  few  F.E.2.B  machines  of  the  Royal  Flying  Corps,  used  for  directing  artillery  fire,  ready  for  a  flight.     (British  official  photo.) 


74 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


The  observer  in  a  £a|itivc  balloon  directing  artillery  fire. 
His  equipment  includes  a  chart  of  the  sector,  divided  in  squares, 
which  enables  him  to  quickly  estimate  the  accuracy  of  the  fir- 
ing. He  transmits  the  information  to  the  battery  commander 
who,  in  turn,  orders  the  gunners  to  fire  according  to  the  in- 
formation received  from  the  observer. 


vary  only  in  detail  and  which  every  student 
should  leam. 

The  pilot,  the  obsen^er,  or  both  remain  close 


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to  the  commander,  or  they  are  notified  to  be  fly- 
ing over  a  certain  spot  at  a  certain  hour. 

An  aeroplane  may  serve  from  one  to  four 
batteries.  When  the  battery  commander 
wishes  to  use  the  aeroplane  to  locate  a  target,  he 
explains  what  he  requires  and,  if  possible,  the 
nature  of  the  target  and  its  general  direction. 
The  aeroplane  then  rises  to  the  necessary  height 
behind  the  battery,  in  order  to  run  less  danger 
of  injuiy  by  hostile  fire.  Meanwhile,  strips  of 
white  cloth  are  laid  out  on  the  ground  near  the 
batteiy,  so  as  to  give  the  supposed  direction  of 
the  target  and  other  instructions.  The  aero- 
plane, having  reached  the  required  height,  flies 
out  over  the  battery  to  find  the  exact  position 
of  the  target. 

The  Observer's  Special  Map 

When  more  accurate  definition  is  wanted  the 
same  method  is  used,  but  the  sides  are  divided 
into  100  parts  and  four  figures  are  used  instead 
of  two.  Thus  0843  denotes  08  parts  East  and 
43  parts  North  of  origin. 

These  maps  contain  as  much  information  as 
is  available  regarding  the  enemy  position,  the 
apparent  importance  of  enemy's  trenches,  en- 
tanglements or  other  obstacles,  fortified  and 
unfortified  mine  craters,  ditches,  railways,  etc. 

There  are  also  shown  in  different  ways,  first, 
second,  and  third  class  roads,  whether  fenced  or 
unfenced;  double-  and  single-track  railways, 
footpaths,  car  tracks,  buildings,  conspicuous 
points,  elevations  (which  are  given  in  meters), 
etc. 


Rrrrlving   mcMagrfi    frmn    tni-    mito   nlisrrvrr,    and    transmitting 
thrm    fo   the   gunnerx. 


A  French  gun  of  large  calibre  being  fir 


DIRECTING  ARTILLERY  FIRE 


75 


A    captive    balloon    observins;    and    directing   artillery   fire    somewhere   in   France   at  dawn. 


There  are  also  shown  the  location  of  trenches 
and  other  prominent  positions  of  the  observer's 
own  forces,  as  it  is  necessary  that  he  know  these. 
While  it  is  true  that  if  the  enemy  captures  one 
of  these  maps  he  obtains  information  regarding 
positions,  it  is  also  true  that  the  enemy  usually 
already  has  that  information,  since  no  such 
supremacy  has  as  yet  been  obtained  as  to  pre- 
vent an  occasional  aeroplane  from  taking  photo- 
graphs or  observing — if  only  from  the  enemy's 
lines,  with  the  support  of  the  anti-aircraft  gvms. 

Signaling  With  Very's  Lights 

When  radio  fails,  Very's  lights  are  used.  In 
this  case  the  observing  aircraft  should  remain 


close  to  their  own  guns,  at  the  best  height  for 
observation,  in  order  to  facilitate  communica- 
tion. In  some  cases,  however,  it  may  be  neces- 
sary to  fly  out  further  toward,  or  even  over, 
the  target  in  order  to  insure  accurate  observa- 
tion. In  such  cases  much  delaj'  will  ensue  if 
the  aeroplane  has  to  come  back  over  its  own 
guns  to  signal  the  results;  on  the  other  hand, 
if  it  remains  out  in  the  front,  the  signals  may 
not  be  seen. 

The  observer  having  located  the  position  of 
the  target  and  conveyed  the  information  to  the 
artillery  commander,  receives  from  him  the  sig- 
nal "Observe  for  line." 

The  aeroplane  now  moves,  keeping  on  that 


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An  officer  of  the  British  Royal  Xavy  Air  Service  shooting  a 
Very  pistol,  used  for  signaling  from  the  aeroplane  to  the  ground 
and  between  aircraft. 

side  of  the  battery  farthest  from  the  sun,  so 
that  the  signals  can  be  easily  seen. 

Rounds  can  only  be  seen  with  ease  when  the 
aeroplane  is  moving  out  toward  the  target.  If 
the  distance  A  to  B  is  about  one  mile,  two 
rounds  can  be  observed  during  each  outward 
flight.  As  soon  as  the  line  is  obtained  the  sig- 
nal "Observe  for  range"  is  sent.  The  aeroplane 
now  moves  in  an  elongated  figure  of  eight,  al- 
ways turning  toward  the  target.     It  will  keep 


behind  or  in  front  of  the  battery,  according  to 
the  position  of  the  sun. 

Range  having  been  obtained,  the  signal  "Ob- 
serve for  fuze"  is  sent,  etc. 

When  the  signal  "Land"  is  sent,  the  aero- 
plane comes  down  at  a  place  previously  selected 
and  not  necessarily  at  the  spot  whence  the  sig- 
nals are  sent. 

Two  men  should  be  detailed  from  the  battery 
to  watch  the  observing  aeroplane,  one  with  field- 
glasses  looking  for  the  signals,  the  other  with 
his  naked  eye  keeping  a  continuous  watch  on  it, 
so  as  to  make  certain  that  no  mistake  is  made 
as  to  the  actual  machine,  since,  when  there  are 
several  aircraft  out  in  observation,  confusion 
between  them  is  very  likely  to  arise. 

With  Very's  lights  the  following  code  of  sig- 
nals may  be  used  for  communication  to  the 
ground. 

Kite-Balloons  for  Spotting  Artillery  Fire 

Kite-balloons  are  used  extensively  for  spot- 
tiiig  artillery  fire.  The  kite-balloons  are  usually 
located  a  few  miles  behind  the  lines  and  the 
balloons  are  sent  up  to  a  height  of  about  two 
thousand  feet,  from  which  the  observers  have  a 
bi'oad  perspective.  For  close-range  observing 
the  kite-balloon  observer  can  do  more  accurate 
work  than  the  aeroplane  observer.  That  is  also 
true  about  observing  at  night.     The  kite-bal- 


U.  S.  Army  Aeroplane 
Xo.  SO  of  the  North  Is- 
land aviation  school 
which  was  one  of  the 
aeroplanes  which  was 
cquipjied  by  Capt.  C.  C. 
Culver  for  radio  work, 
the  aerial  wires  being 
shown  above  the  upper 
plane  in  the  picture. 
I.ieut.  Herbert  Dargue, 
I'.  S.  A.,  is  seen  at  the 
])ilot's  wheel,  while  Major 
Frank  P.  I.nhm  is  in  the 
observer's  seat.  The  of- 
ficers had  just  completed 
a  flight. 


DIRECTING  ARTILERY  FIRE 


77 


Rigging  up  the  -wireless  receiving  post  be- 
tween two  wireless'  motor  truclts  "somewhere 
in  France." 


loon  observer,  having  knowledge  of  his  own 
position,  can  easily  figure  out  the  location 
of  any  light  which  he  may  see,  or  of  the  flashes 
of  hostile  guns.  The  kite-balloon  observer 
transmits  the  information  by  telephone  to  the 
officer  below,  who  transmits  it  to  the  battery. 

The  Dubilier-GoU  Semi-Radio  Telephone 
System  for  Captive  Balloons 

Communicating  from  an  observer's  balloon 
to  the  battery  commander  is  usually  done  by 
means  of  the  regular  standard  telephone  instru- 
ments operated  by  a  few  dry  cells,  using  two 
wires,  the  same  as  with  the  ordinary  house  tele- 
phone. The  holding  cable  of  the  balloon, 
which  is  used  for  hauling  the  balloon  up  and 
down,  is  especially  constructed  in  such  a  way 
that  it  has  a  small  insulated  wire  in  the  center, 
which  is  used  for  the  return  circuit.  This  in- 
sulated wire  makes  the  cable  not  only  expensive, 
but  weak  in  construction,  especially  when  over 
2000  feet  are  used,  when  the  strain  on  the  cable 
can  be  seen  from  the  height  of  3000  ft.,  and  a 
prearranged  code  of  signals  can  be  made  by 
this  means. 

Very's  lights  fired  from  the  ground  can  be 
seen  from  aircraft  with  the  same  ease  as  those 
fired  from  the  air  can  be  seen  from  the  ground, 
if  the  observer  knows  exactly  where  to  look  for 
them. 

Signaling  between  Aircraft 

It  is  possible  to  signal  between  airships  with 
a  signal  flag  by  semaphore  or  ISIorse  code,  pro- 


vided the  aircraft  are  broadside  to  each  other, 
and  not  over  1000  yards  apart. 

Between  aeroplanes,  Very's  lights  can  be 
used  in  accordance  with  a  prearranged  code. 

Major  C.  C.  Culver,  U.  S.  Army,  who  has 
done  much  important  pioneer  work  in  radio  so 
applied  to  aeronautics,  and  is  mainly  responsible 
for  placing  the  United  States  foremost  in  this 
science,  has  evolved  a  method  which  permits 
intercommunication  between  aircraft  in  flight  by 
wireless  telephone. 

Cooperation  between  Balloons  and  Artillery 

By  Major  D.  RAINSFORD  HANNAY 
British  Royal  Flying  Corps 

Courtesy  of  "Aerial  Age  Weekly" 

It  is  a  very  well-known  axiom  in  war  that 
the  closest  co-operation  between  the  various 
arms  is  necessary  to  secure  the  best  residts ;  and, 
when  it  comes  to  the  question  of  captive  bal- 
loons observing  for  artillery,  the  more  that  each 
imit  knows  about  the  methods  of,  and  the  diffi- 
culties experienced  by,  the  other  the  better. 

I  propose,  therefore,  to  describe  the  working 
of  a  balloon  section  of  the  British  Army  in  the 
field. 

As  regards  organization,  the  balloon  service 
of  the  Royal  Flying  Corps  is  divided  into  wings, 
companies,  and  sections.  A  section  consists  of 
four  officers  and  90  men  and  works  one  bal- 
loon. A  company  consists  of  two  sections.  A 
wing  consists  of  all  the  companies  in  any  one 
army. 

The  balloon  now  in  use  in  the  field  is  a  stream- 


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line  balloon,  the  invention  of  Captain  Caquot, 
of  the  French  Army.  It  has  a  cubic  capacity 
of  950  cubic  meters  and  is  capable  of  lifting  two 
observers  to  a  height  of  4000  feet.  Each  sec- 
tion is  provided  with  a  mobile  winch,  the  engine 
of  the  winch  being  quite  separate  from  the  en- 
gine of  the  truck  on  which  the  winch  is  mounted. 
Theoretically,  the  balloon  should  be  let  up  from 


J' 


the  ground  at  a  considerable  distance  behind 
the  lines  and  then  run  forward  on  the  winch 
with  the  balloon  high  up  in  the  air;  but,  in 
practice,  it  is  found  that  there  are  very  few 
roads  left  near  the  lines  which  are  fit  for  a  heavy 
truck,  and,  even  if  one  is  found,  it  is  probably 
too  congested  with  traffic.  Owing  to  these  rea- 
sons, the  majority  of  balloons,  in  France,  are 
stationary,  at  an  average  distance  of  about  6000 
yards  behind  the  line.  Where  sections  have 
been  able  to  move  their  winches  forward,  they 
have  got  within  4000  yards  of  the  front  line. 
As  regards  observation  of  fire,  the  work  of 


the  balloon  observer  is  chiefly  with  the  heavier 
pieces  of  artillery,  such  as  the 

6-inch  howitzers  and  the  4.7-inch  guns, 

8-inch  howitzers  and  the  60pounder  guns, 

9.2-inch  howitzers  and  the  6-inch  guns, 

12-inch  howitzers,  ' 

15-inch  howitzers. 

In  the  earlier  days  of  the  war,  when  there 
were  fewer  heavy  batteries,  balloons  used  to  ob- 
serve for  Field  Artillery,  but,  owing  to  the 
great  increase  of  the  howitzer  batteries,  and, 
also,  to  the  somewhat  altered  role  of  the  Field 
Artillery,  very  little  work  is  done  with  them 
nowadays.  In  order  to  avoid  confusion.  Field 
Artillery  in  the  British  Army  consists  of  only 
18-pounder  guns  and  4.5-inch  howitzers. 

The  balloon  section  is  connected  by  telephone 
to  all  the  batteries  with  which  it  is  likely  to 
work.  The  sketch  gives  a  typical  communica- 
tion scheme  of  a  section  in  the  field.  The  up- 
keep of  the  telephone  service  is  most  important, 
and  it  is  necessary  that  batteries  should  give 
as  much  mutual  assistance  as  possible.  Unless 
the  lines  are  working  well,  the  balloon  might 
as  well  be  on  the  ground,  for  all  the  good  it 
can  do.  An  advantage  which  a  balloon  has  over 
an  aeroplane,  and  one  that  compensates  for  a 
great  many  of  the  disadvantages,  is  the  fact  that 
the  observer  in  the  basket  can  talk  direct  by 
telephone  to  the  batterj'  commander  on  the 
ground,  and  does  not  have  to  confine  himself 
to  a  limited  code  as  used  on  the  wireless.  To 
refer  to  the  sketch,  all  the  telephone  lines, 
shown,  with  the  exception  of  those  to  Corps 
Heavy  Artillery  Headquarters,  are  the  shoot- 
ing lines  of  the  section,  and  are  used  only  when 
observing  for,  or  when  arranging  shoots  with, 
batteries.  Lines  lead  from  the  balloon  camp 
exchange  to  an  advanced  exchange  which  is 
placed  in  a  central  position  among  the  batteries. 
Now  when  the  balloon  is  in  the  air,  it  is  con- 
nected by  a  telephone  cable  to  the  winch,  which 
is,  in  turn,  connected  by  aerial  line  to  the  camp 
exchange,  and,  tapped  in  one  this  line,  is  the 
chart  room  of  the  section,  where  all  the  map 
work  and  the  arranging  of  shoots  with  batteries 
are  done. 

I  have  purposely  enlarged  on  the  commnni- 


DIRECTING  ARTILLERY  FIRE 


79 


•  ,  '  •\  ••  -  ■•■'••.■•'."•.   ...  ■ 

.\  AREA     IN  'PLAr^E  OF  PURSUER^  -  .     - 

.•  ■  .  PrtOPEI-LER'  COVERED     BY  ■  • .  •. 

•'  *•  ■  .'    ]  FIRt    OF  l/PPER  GUN  .      •  ."  ■• 


area  in  pl.-.he  of  purs0er"5   propelter 
through  which  upper  gun    cannot  pirc 
Without  damac«nc  own  tail    ' 


How  the  Gotha  Gunners  protect  the  rear  or  "blind"  side  from  attacks. 


The  German  Gotha  battleplane,  famous  for  its  raids  on  British  soil. 


80 


TEXTBOOK  OF  MILITARY  AEROXAUTICS 


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cations  of  a  section  for  this  reason :  although  the 
greater  part  of  the  hnes  are  laid  by  the  signal 
companies,  when  once  laid,  the  balloon  section 
is  responsible  for  their  upkeep,  and  it  will  be 
seen,  on  referring  to  the  sketch,  that  it  is  a 
pretty  big  job  for  the  small  telephone  detach- 
ment allotted  to  a  balloon  section.  Therefore 
it  is  of  the  greatest  help  when  batteries  assist, 
as  much  as  is  in  their  power,  with  the  laying  and 
maintenance  of  the  line  from  their  position  to 
the  advanced  exchange   ( see  Fig.  1 ) . 

The  work  chiefly  allotted  to  the  balloon  con- 
sists of: 

1.  Destruction  of  villages; 

2.  Destruction  of  strong  points  behind  the 
line; 

3.  Registering  on  cross  roads; 

4.  Registering  on  exits  from  villages,  woods, 
and  ravines; 

5.  Counter-batterj'  work. 


The  method  of  observation  employed  it  to 
observe  on  the  line  balloon-target,  and,  bj'  the 
use  of  graticuled  glasses,  to  send  to  the  battery 
such  observations  as 

1°20'  Right, 
30'  Left, 

Line  and  over. 

Line  and  short. 

When  the  battery  sends  "Gun  fired,"  the 
chart  room  officer  sets  his  stop-watch  going  and 
says,  "Bun  fired"  to  the  observer,  then,  at  the 
correct  time:  "10  seconds  to  burst";  "5  seconds 
to  burst";  "4";  "3";  "2";  "1";  "Burst." 

This  relieves  the  observer  in  the  balloon  of 
watching  with  his  glasses  the  whole  time.  He 
nmst  keep  his  eyes  fixed  on  the  target,  but  need 
not  strain  them  by  peering  through  his  glasses 
during  the  whole  time  of  flight.  When  he  hears 
"10  seconds"  he  gets  ready,  and  at  "5"  puts 
them  up. 


i 


A  French  captive  balloon  of  the  Caqout  type  just  behind  the  firing  lines. 


CHAPTER  VII 
KITE  BALLOONS  -THE  EYES  OF  THE  ARTILLERY 

Written  by  a  French   Officer;  Translated  by  Augustus  Post 
(From  "Lectures  Pour  Tous") 


Another  of  the  marvelous  developments  of 
the  war  is  the  captive  balloon,  which,  in  view  of 
the  wonderful  progress  made  with  dirigibles 
and  aeroplanes,  seemed  doomed  to  be  relegated 
to  the  storehouse.  Captive  balloons,  on  the 
contrary,  have  developed  with  the  increasing 
importance  of  artillery  until  we  now  receive 
most  valuable  service  from  our  "sausages," 
which  are  exposed  to  great  dangers  and  whose 
officers  have  had  most  dramatic  adventiu'es. 

Holding  the  lines  of  the  enemy  under  con- 
tinuous observation,  transmitting  to  the  com- 
mander every  operation  that  goes  on,  directing 
artillery  fire — this  is  the  role  that  the  captive 
balloon  plays.  Before  the  beginning  of  the 
war,  the  Germans  had  foreseen  their  value  and 
although  we  had  only  spherical  captive  balloons, 
they  were  already  using  the  elongated  shape, 
familiarly  called  "sausage."  As  is  the  case 
with  many  other  inventions,  this  model  was 
originally  French,  and  was  copied  and  adapted 


by  the  Germans  under  the  name  of  "drachen," 
or  "kite"  balloon.  It  has  proven  its  superior- 
ity since  the  spring  of  1915,  because  it  acts  ex- 
actly as  a  kite  and  is  supported  by  the  force  of 
the  wind,  when  a  spherical  balloon  woidd  be 
beaten  down  by  a  wind  of  from  eight  to  ten 
meters  a  second. 

Manoeuvering 

A  balloon  company  consists  of  a  crew,  who 
take  charge  of  the  manoeuvering  of  a  kite  bal- 
loon; that  is  to  say,  filling,  observation,  trans- 
porting, and  making  the  ascension.  In  addi- 
tion, there  are  several  wagons  and  automo- 
biles. The  most  important  is  the  "voiture- 
treuil,"  or  "windlass  wagon."  A  steel  cable 
about  the  size  of  a  pencil,  that  can  stand  a 
heavy  pull,  is  wound  up  on  an  immense  reel.  In 
the  center  of  this  cable  is  a  telephone  wire,  con- 
necting with  the  basket.    A  motor  turns  the  reel 


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in  one  direction  or  the  other  to  allow  the  balloon 
to  ascend,  or  to  draw  it  down.  The  automobile 
windlass  has  almost  entirely  superseded  the  old- 
fashioned  steam  winch  with  six  or  eight  horses ; 
it  moves  three  or  four  times  as  fast,  needs  not 
more  than  ten  meters  to  turn,  and  is  less  vul- 
nerable. Always  ready,  it  is  easily  concealed 
with  a  cover  of  branches. 

Camp  Equipment  of  a  Kite  Balloon  Unit 

^^^len  the  balloon  is  in  use,  the  "treuil"  is  ac- 
companied by  a  "camion  aux  agres,"  or  "rig- 
ging truck"  containing  a  store  of  extra  ropes, 
the  basket,  the  "godets,"  or  cup-shaped  pieces 
which  are  attached  back  to  back  and  make  an 
immense  kite-tail  to  head  the  balloon  into  the 
wind.  The  equipment  includes  the  field- 
glasses,  maps,  and  scientific  instruments.  Be- 
sides the  windlass  wagon,  there  are  two  equally 
important  wagons  that  hold  the  encampment 
paraphernalia  and  the  telephone  equipment. 
The  first  has  all  the  things  necessary  to  set  up 
a  new  observation  station  when  the  old  one  has 
to  be  abandoned  for  some  cause — shell-fire,  for 
instance,  coming  too  near.  They  carry  cork- 
screw stakes  and  pegs  which  hold  the  stays  of 
the  balloon,  sacks  of  ballast,  a  ground-cloth  to 
prevent  the  balloon  touching  the  ground,  and 
all  the  other  things  that  are  a  necessary  part 
of  the  equipment.  In  one  day  a  company 
changed  its  location  four  times,  because  the  posi- 
tions were  shelled  each  time  after  the  balloon 
had  been  set  up  and  inflated. 


The  telephone  car  contains  all  the  material 
necessary  to  establish  communication, — miles  of 
wire,  apparatus,  tables,  bells,  spurs  for  climbing 
high  trees,  insulators  and  brackets  for  laying 
lines  to  connect  the  balloon  with  the  commander 
of  the  artillerv  or  batteries  of  anti-aircraft  ffuns, 
if  they  are  a  long  way  from  the  place  of  ascen- 
sion. 

An  Artillery  Captain's  Experience 

During  an  advance,  the  observer  in  the  basket 
is  directly  in  touch  with  the  gunners  and  regu- 
lates their  fire,  a  very  interesting  occupation  for 
the  observer,  especially  when  it  is  necessary  to 
pick  off  some  convoy  or  troop  on  the  march. 
One  day  an  old  captain  of  artillery  who  had  lit- 
tle confidence  in  the  usefulness  of  the  captive 
balloon  was  invited  to  ascend,  in  order  to  see 
how  easy  it  was  to  control  the  artillery  fire. 
They  had  not  ascended  one  hundred  meters  be- 
fore he  marveled  at  the  panorama,  at  three  hun- 
dred he  was  converted,  at  eight  hundred  he  was 
enthusiastic.  The  observer  who  accompanied 
him  kept  revealing  new  possibilities  to  him  all 
the  time.  The  time  passed  until  the  ofiicer  com- 
manding the  company  of  the  balloon  corps  saw 
his  telephone  operators  bursting  with  laughter. 
He  called  them  to  order,  thinking  that  they  were 
telling  each  other  funny  stories,  but  one  of  them 
said  to  him,  "Take  the  receiver  and  listen  to 
the  observer  and  the  captain  in  the  balloon." 
They  were  directing  fire  upon  a  long  train  on 
the  march,  at  the  extreme  range  of  a  battery. 


One  of  the  monster 
British  guns  on  the  West- 
ern front.  The  efficiency 
of  these  guns  Hei>ends  en- 
tirely on  the  spotting  of 
tlie  (lerial  ohservers,  there- 
fore. The  Kite  halloons 
are  usually  stationed  in 
the  rear  of  heavy  artil- 
lery, held  anchored  by 
means  of  cnhles.  The  ob- 
servers in  the  basket  of 
the  balloon  have  a  clear 
view  of  the  enemy's  posi- 
tion and  observe  the  re- 
sults of  the  gun  firing, 
and  advise  the  battery 
commanders  by  telephone. 


KITE  BALLOONS— THE  EYES  OF  THE  ARTILLERY 


88 


f 


Photograph  taken  from  kite  balloon  showing  how  the  earth  appears  to  an  observer. 


The  captain  was  amazed  and  could  not  restrain 
himself.  "Bang!  in  the  center;  one  wagon  de- 
molished. Oh!  and  the  horses — bang! — an- 
other. Eh! — Ah!  it  is  wonderful,  wonderful. 
I  never  believed  it.  Bang!  At  least,  we  do  not 
fire  blindly." 


Personnel  of  Kite  Balloon  Company 

The  personnel  of  a  company  of  balloonists 
is  divided  into  two  classes  of  about  equal  num- 
bers; that  is  to  say,  the  men  who  pull  on  the 
ropes,  and  the  others.  In  order,  they  are:  the 
captain,  sometimes  a  lieutenant,  in  command  of 
the  company.  It  is  he  who,  assisted  by  his  offi- 
cers, chooses  the  best  point  for  observation  and 
the  most  convenient  for  locating  the  balloon  and 
the  camp.  Under  the  direction  of  the  officers, 
the  sergeants  assign  the  corporals  to  their  ropes, 
and  lay  out  and  transport  the  balloon  over  ob- 
stacles. Eight  men  handle  the  envelope,  and 
the  rigging,  place  the  basket,  and  adjust  the 
maps  and  instruments,  four  or  five  mechanicians 
work  the  winch,  and  one  cyclist  and  one  motor- 
cyclist serve  as  messengers.  As  in  all  other 
troops,  there  is  a  doctor,  a  quartermaster,  a  fur- 
rier, tailor,  shoemaker,  barber,  orderlies,  and  all 


the  little  world  of  specialists  who  go  to  make  up 
an  efficient  unit. 


Preparations  for  Ascension 

When  a  company  arrives  at  a  new  position 
the  captain,  accompanied  by  his  observers,  im- 
mediately gets  in  touch  with  the  commanders  of 
artillery,  inquires  the  location  of  the  enemies' 
batteries,  their  habits  and  activities,  and  the 
strength  of  their  artillery  and  aeroplanes.  In 
another  direction  a  mounted  officer  with  a  detail- 
map  searches  for  a  good  location  to  station  the 
balloon.  This  is  a  very  delicate  matter  to  de- 
cide. The  best  place  is  in  a  forest,  which  pro- 
tects the  balloon  from  high  winds.  Trees  are 
cut  down  to  make  a  clearing  large  enough  for 
the  manoeuvers  of  ascending  and  descending 
without  risk  of  tearing  the  envelope  on  the 
branches,  and  for  leaving  room  to  handle  the 
tail  of  parachutes.  Next  the  work  of  making 
camp  is  begun.  The  ground-cloth  is  spread,  ten 
stakes  set,  to  attach  the  balloon,  80  ballast  sacks 
of  ten  kilos  are  placed  with  their  hooks  in  the 
network,  and  a  bag  containing  the  balloon  is 
placed  in  the  center  of  the  ground-cloth.  The 
valve  is  attached,  the  cords  straightened  out, 


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and  the  filling  pipe  securely  connected.  All 
this  takes  about  half  an  hour,  and  the  balloon 
is  ready  for  inflation.  Hydrogen  is  brought  in 
from  the  tube  wagons,  each  tube  containing  150 
cubic  meters  of  gas,  compressed  to  a  small  vol- 
ume. It  takes  over  one  hundred  tubes  to  fill  the 
balloon,  and  from  two  to  three  hours,  unless  you 
have  enough  tube  wagons,  when  it  can  be  done 
in  half  an  hour.  When  filled,  the  "sausage"  is 
ready  to  ascend,  if  the  weather  permits  and  the 
wind  is  moderate. 

In  fifteen  minutes  the  balloon  is  in  the  air,  not 
to  come  down  till  nightfall,  and  the  regular  rou- 
tine of  life  begins.  At  daylight  the  company 
return  to  the  balloon.  Some  detach  the  ropes 
from  the  fastenings  and  unhook  the  bags  of  bal- 
last which  hold  it  down,  while  others  connect 
the  appendix,  and  replace  the  gas  lost  during 
the  preceding  ascension  by  expansion,  due  to  the 
altitude.  This  takes  only  fifteen  or  twenty  min- 
utes at  most,  and  soon  all  is  ready  for  another 
ascension.  When  circumstances  permit,  the 
balloon  remains  in  the  air  all  the  time,  with  one 
or  two  observers  who  take  their  meals  with  them. 
As  night  falls,  or  when  the  weather  renders  it 
useless  to  remain  in  the  air,  or  dangerous  storms 
with  rain  or  high  winds,  come  up,  the  balloon  is 
brought  down,  disconnected,  and  made  fast  for 
the  night  under  the  watch  of  sentinels,  so  that 
the  rest  of  the  men  can  return  to  camp.  Fre- 
quently, it  is  necessary  to  remain  ujj  all  night. 


to  search  out  the  batteries  of  the  enemy  by  the 
flashes  from  his  guns.  An  observer  who  has 
passed  many  days  in  a  balloon  becomes  famihar 
with  the  countrj^  and  can  determine  in  the  dark 
various  points  in  the  landscape  and  tell  where 
certain  woods  and  villages  lie,  or  he  can  even  lo- 
cate very  exactly  a  batterj'  whose  position  could 
not  be  located  in  the  daytime.  This  routine  con- 
tinues with  great  regularity,  until  the  company 
receives  orders  to  take  up  a  new  position.  In 
three  or  four  hours  at  most  the  convoy  is  on  the 
march,  the  balloon  being  deflated  in  twenty-five 
minutes,  and  packed  in  its  sack,  and  all  other 
materials  loaded  on  the  wagons. 

What  You  Can  See  from  a  Kite  Balloon 

Here  is  a  story  of  a  lieutenant  of  artillerj^  on 
his  first  ascension. 

"The  order  to  'let  go'  has  been  given.  ]My 
basket  is  a  charming  little  boudoir,  hardly  big 
enough  to  take  two  steps  in.  At  my  hand,  hter- 
ally,  are  three  binoculars,  maps,  and  the  tele- 
phone which  connects  with  the  ground  and  puts 
me  in  direct  connection  with  the  commander  of 
the  artillery  station.  At  my  feet,  I  see  my  com- 
panions looking  up,  with  their  heads  thrown 
back.  The  perspective  rapidly  extends.  The 
horizon,  limited  by  the  trees  and  surrounding 
hills,  slips  farther  and  farther  away;  the  land- 
scape stretches  out  below  in  relief;  the  picture 
changes  to  a  geographical  map,  but  the  map  is 


One  of  the  hundreds  ot  French  motor  batteries  en  route  to  its  firing  point,  the  Are  of  which  is  directed  by  Kite  balloons  and 

aeroplanes. 


KITE  BALLOONS— THE  EYES  OF  THE  ARTILLERY 


85 


vivid  and  brilliant  with  soul-inspiring  color ;  ser- 
pentine roads  and  rivers  stretch  away  in  the  dis- 
tance. Just  below  me  is  a  farm,  and  those  mi- 
nute dots  are  animals.  In  the  east,  a  few  kilo- 
meters away,  are  the  zigzag  lines  of  the  enemy's 
trenches ;  they  cross  and  re-cross.  In  the  center 
runs  a  slender  green  ribbon  which  seems  to  be 
intact.  This  is  the  ground  between  the  trenches 
of  our  first  line,  and  the  enemy.  Here  and 
there  are  some  ruined  villages,  the  houses  de- 
mohshed.  The  desolation  of  the  scene  makes 
one  feel  sad.  Scattered  all  about,  we  can  see 
black  and  white  places.  These  are  the  shell- 
holes,  where  the  enemy  has  trained  a  battery 
upon  some  spot  and  sprinkled  it  with  terrific  fire. 
There  are  also  our  own  works,  and  batteries 
which  we  know  well  by  the  puffs  of  smoke  when 
the  guns  are  fired.  From  the  basket  all  this  is 
perfectly  clear.  It  is  the  ideal  observatory  for 
artillery.  It  is  true  that  the  basket  is  not  al- 
ways above  the  positions  of  the  enemy,  as  is  the 
case  with  the  aeroplane,  but  it  is  stable,  and  you 
can  use  glasses  without  difficulty.  There  is  also 
another  great  advantage  in  that  the  observer  is 
in  constant  communication  with  his  batteries, 
which  is  more  accurate  and  rapid  work  than  in 
the  case  of  the  aeroplane." 

Aeroplane  vs.  Captive  Balloon 

The  captive  balloon  has  a  dangerous  enemy — 
the  aeroplane.     When  the  weather  is  clear  and 


An  aeroplane  having  approached  the  balloon,  the  observer  has 
jumped  into  space  and  is  descending  by  means  of  the  para- 
chute. 

the  clouds  high,  the  aeroplane  is  not  a  formid- 
able enemy.  The  telephone  signal  and  white 
pufPs  of  smoke  from  the  "75's"  give  warning 
from  afar.  If  the  balloon  is  too  high,  it  is 
hauled  down  300,  400,  or  500  meters,  but  not 
down  to  the  ground,  for  if  it  is  on  the  ground, 
the  enemy  aviator  has  only  to  consult  his  map 


A  French  Kite  balloon 
being  inflated.  The  Ger- 
mans were  first  to  em- 
ploy Kite  balloons  for 
directing  artillery  fire. 
The  Allies  promptly 
adopted  them  and  now 
there  are  thousands  of 
Kite  balloons  in  use  on 
both  sides  and  are  con- 
sidered absolutely  inval- 
uable. The  English  call 
it  "Kite  balloon,"  the 
French  "balloon  captif" 
or  "saucisse,"  the  Russian 
"Kolbasa,"  the  German 
"drachen,"  the  Italian 
"Pallone  —  Cervo  Vo- 
lante." 


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and  altimeter  to  know  his  exact  lieight  above  his 
target  and  release  his  bombs  with  some  chance 
of  success.  If  the  balloon  is  at  an  unknown 
height,  it  is  impossible  for  the  aviator  to  calcu- 
late the  instant  to  let  fall  his  projectile.  When 
he  descends  low  enough  to  attack  with  his  ma- 
chine gun,  he  must  risk  being  hit  by  the  ob- 
server's gun-fire  and  the  machine-gun  below  the 
balloon.  Descending  to  2000  meters  is  dan- 
gerous for  the  aviator,  but  there  are  some  excep- 
tions of  which  the  following  incident  is  one : 
Last  jNIarch,  in  ideal  weather,  the  balloon  of 

the Company  was  in  a  clear  sky  at  sunset. 

Suddenly  the  signal  came  that  a  German  aero- 
plane was  seen  on  the  horizon.  In  truth,  all  one 
could  see  was  the  white  puffs  from  the  "75's" 
shells,  high  in  the  sky.  But  soon  the  silhouette 
of  an  aeroplane  appeared,  making  right  for  the 
balloon.  A  whistle,  two  or  three  sharp  com- 
mands, and  the  windlass  commenced  to  haul  in 
while  the  machine-guns  and  muskets  were 
trained  on  the  aeroplane,  and  the  observer 
warned  by  telephone.  There  was  no  more 
doubt,  for  not  only  had  the  aeroplane  headed  for 
the  balloon,  but  again,  without  heeding  the 
bursting  shells,  pointed  directly  at  the  "sau- 
sage." Descending  with  great  daring  to  the 
same  height,  so  that  it  was  difficult  for  the  anti- 
aircraft guns  to  regulate  their  fire,  the  machine- 
guns  only  were  brought  into  action.  In  the 
basket  Adjutant  T.,  just  promoted,  prepared 


to  christen  his  chevrons;  his  carbine  came  into 
play.  Seeing  the  balloon  descend,  the  German 
aviator  volplaned  down,  so  near  that  we  hoped 
each  instant  he  would  be  caught  in  the  manoeu- 
vering  rope.  While  turning,  the  aviator  was 
furiously  firing  his  machine  gun.  As  luck 
would  have  it,  the  carbine  of  the  observer 
jammed.  He  kept  cool,  however,  which  was 
easily  done,  for  it  was  6°  above  zero,  and  calmly 
sat  down  in  the  bottom  of  the  basket  trying  to 
fix  his  gun.  Believing  him  wounded  the 
"boche,"  despite  the  bullets  which  whistled 
around  him,  tried  to  set  fire  to  the  "sausage" 
with  a  specially  constructed  cannon.  He 
launched  an  incendiary  bomb,  and  we  saw  a 
train  of  glowing  sparks  go  toward  the  balloon. 
But  Adjutant  T.  had  fixed  his  gun.  He  rose 
in  the  basket  and  fired  point  blank  at  the  enemy. 
Alas !  he  fired  only  four  shells  when  the  breech- 
block broke,  leaving  him  completely  disarmed, 
while  the  German,  with  a  new  machine-gun, 
merely  unrolled  a  new  belt  of  250  cartridges. 
Finally  a  French  aviator,  who  had  seen  the 
struggle  from  afar,  flew  up  to  the  rescue.  The 
aviatik  flew  away,  pursued  by  the  "75's." 
Brave  Adjutant  T.  was  safe  and  sound,  but  the 
basket  and  envelope  were  riddled  with  bullets. 
This  damage  was  repaired  with  a  few  patches. 

Such  a  bold  attack  is  exceptional,  but  some- 
times the  aviator  uses  other  tactics  to  attack  the 
balloon.     He  chooses  a  day  when  great  clouds 


A  Russinn  observntion  balloon 
and  its  "nurse."  An  oljserva- 
tion  balloon  after  inflation  may 
stay  in  the  air  for  an  entire  day 
without  receiving  additional  gas. 
When  it  needs  replenishing  a 
smaller  balloon,  the  "nurse,"  is 
brought  up  and  the  gns  it  eon- 
tains  is  pressed  info  the  larger 
balloon,  the  pressing  being  done 
by  the  men,  who  squeeze  the 
"nurse." 


KITE  BALLOONS— THE  EYES  OF  THE  ARTILLERY 


87 


form  in  a  layer  above  the  balloon,  two  or  three 
thousand  meters  high.  Flying  above  the 
clouds,  the  aviator,  seeing  his  prey  through  a 
rift,  or  judging  he  is  near  enough,  darts  down, 
releasing  his  incendiary  bombs  covered  with  fish- 
hooks, which  catch  in  the  envelope  and  are  sure 
to  set  it  afire.  Another  of  these  tactics  is  to 
take  advantage  of  the  clouds  that  pass  between 
the  balloon  and  the  ground,  hiding  the  aeroplane 
from  the  eyes  of  the  balloon  company,  who  are 
unable  to  train  their  machine  guns  upon  the 
enemy. 

A  Leap  Into  Space  from  a  Kite  Balloon 

Experience  has  taught  that  the  counter -move 
for  this  manoeuver  is  not  to  allow  the  balloon  to 
rise  out  of  sight  above  the  clouds  and,  when 
necessary,  to  haul  it  down  by  the  winch  every  lit- 
tle while.  The  observer  is  also  provided  with 
a  parachute,  which  he  attaches  to  his  back  by 
stout  suspenders  which  pass  under  his  arms  and 
around  his  waist.  If  he  finds  his  balloon  on  fire, 
or  if  warned  by  the  telephone  from  the  ground, 
he  jumps  out.  The  parachute,  folded  in  a  spe- 
cial sack,  opens  in  less  than  sixty  meters,  land- 
ing him  gently  on  the  ground.  This  is  of  quite 
frequent  occurrence.  Within  three  days  the 
life  of  an  observer  was  saved  on  two  occasions 
by  this  means.  On  the  19th  of  March,  during  a 
violent  wind-storm,  the  rigging  broke,  and  two 


The  observer  descending  with  the  parachute  to  escape  an  aero- 
plane attack. 


seconds  later  the  basket  started  to  fall.  In- 
stinctively the  observer  saw  his  danger,  gathered 
up  his  papers,  jumped  into  space  and  descended 
with  his  parachute.     When  his  feet  touched  the 


Turning  on  the  gas 
from  gas  cylinders  to  in- 
flate a  Kite  balloon. 
M'herever  a  Kite  balloon 
is  established  there  are 
brought  the  gas  cylinders 
on  specially  constructed 
trucks.  They  are  then 
unloaded  and  placed  on  a 
.special  stand,  as  shown  in 
the  photo,  and  pipes  are 
connected  to  each  cylin- 
der and  to  the  main  pipe 
which  is  connected  to  the 
rubber  tube  which  leads 
to  the  ai)pendix  of  the 
Kite  balloon. 


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Members   of  the   Canadian   Kite   Balloon   Section   patcliing  up   a 
kite  balloon  on  the  Somme  front. 

ground,  the  eighty  square  meters  of  cloth  made 
a  sail  in  the  strong  wind  and  he  was  dragged 
1200  meters  over  the  fields,  finally  bringing  up 
with  only  a  few  scratches. 

A  Curious  Manoeuver 

"When  the  wind  rages  and  the  rain  falls,  the 
windlass  is  used  to  bring  the  balloon  down,  but 
if  it  breaks,  they  use  a  "tiraudes,"  or  snatch 
block  with  eight  large  ropes  attached  to  it. 
!Men  pull  on  this  rope,  marching  straight  away, 
bringing  the  balloon  down  to  the  ground  one 
half  as  fast  as  the  winch.  A  serious  situation 
may  arise  if  the  windlass  is  destroyed  by  shell- 
fire  and  the  balloon  cut  away  when  the  wind  is 
blowing  toward  the  enemy's  lines.  When  this 
happens,  they  move  the  automobile  winch  away, 
dragging  the  balloon  like  a  kite.  Of  course  the 
observer  can  always  descend  by  opening  the 
valve  and  allowing  the  gas  to  escape. 


\ 


A  Drama  at  the  End  of  a  Cable 


Accidents  will  happen  despite  all  precautions. 
Last  spring  there  was  a  tragic  day  for  our  bal- 


loons when  several  were  torn  away  by  the  wind 
and  driven  over  the  enemy's  lines.  The  weather 
kept  the  balloons  down  all  day  until  about  5 :30 
P.  M.,  when  it  cleared  and  the  wind  fell  to  a  flat 
calm,  the  kite  tails  hanging  vertically  along  the 
cable.  Two  officers  went  up  in  one  of  the  bal- 
loons. They  wished  to  go  high  enough  to  ob- 
serve a  battery  that  had  had  the  cover  which  con- 
cealed it  blown  away.  To  lighten  the  balloon, 
they  left  the  only  parachute  in  the  equipment 
on  the  ground.  Suddenly  the  telephone  op- 
erator called  the  observer  and  said,  "Heavy 
clouds  are  forming  in  the  southwest."  Rapidly 
the  sky  became  overcast  and  in  an  instant  the 
balloon,  which  had  been  hanging  directly  over- 
head, started  northeast.  The  wind  rose,  and 
the  Captain  ordered  the  windlass  to  haul  down 
as  quickly  as  possible.  Two  hundred  meters 
were  wound  on  the  drum,  and  a  thousand  still 
remained.  The  winch  puffed  and  labored,  and 
finally  stopped  altogether.  "Raise  the  pres- 
sure," ordered  the  Captain.  "I  have  eight  kil- 
ograms," answered  the  engineer.  The  pressure 
cannot  be  raised  in  a  moment,  and  time  was  fly- 
ing. The  windlass  turned  slowly,  and  again  it 
stopped.  "Ever}"  one  on  the  hauling  ropes," 
came  the  order,  as  a  last  resort.  Two  hundred 
meters  were  hauled  in  this  way,  when  the  men 
walking  away  with  the  rope  were  blocked  by  a 
large  farm  building  and  had  to  halt. 

At  this  moment  the  engineer  signaled  that  the 
pressure  was  at  ten,  the  extreme  limit  of  the 
gage,  and  again  the  winch  began  to  turn. 
Hopes  arose,  but  the  wind  arose,  too.  The  rope 
jumped  the  groove  of  the  pulley,  became 
jammed,  and  the  winch  stopped.  "To  the  haul- 
ing ropes  again,"  the  Captain  cried.  INIean- 
while  there  was  another  drama  at  the  other  end 
of  the  cable  on  which  hung  the  life  of  two  men. 
The  "sausage"  tugged  at  its  mooring  line,  like 
a  horse  champing  his  bit.  The  basket  swayed, 
capsized  and  swung  like  a  .stone  in  a  sling.  The 
telephone  was  not  yet  broken.  From  the  bot- 
tom of  the  basket  one  of  the  unfortunates 
shouted,  "One  more  jerk  will  be  our  la.st."  The 
other  cried,  "It  is  all  over  with  us."  Alas,  his 
presentiment  was  only  too  true.  The  basket 
tossed  in  the  air.  The  .stabilizing  wings  of  the 
balloon  were  torn  off.     The  balloonet  ripi)ed 


KITE  BALLOONS— THE  EYES  OF  THE  ARTILLERY 


80 


into  shreds,  diabolically  whipping  the  air.  One 
after  another  the  strands  of  the  cable  broke. 
The  balloon,  freed  from  its  leash,  leaped  into  the 
air,  the  light  car  swaying  below.  It  was  a  tragic 
moment ;  there  was  a  lull  in  the  midst  of  the  con- 
fusion, but  the  poor  men  in  the  basket  were  per- 
fectly calm.  No  more  jerks  terrified  them,  but 
what  was  worse,  they  were  borne  in  the  direction 
of  the  enemy's  line.     We  saw  objects  fall  from 


the  car.  They  were,  as  we  found  out  later,  the 
maps  and  secret  papers  which  the  brave  men  had 
had  the  presence  of  mind  to  think  of  and  throw 
down  before  passing  over  the  lines.  This 
drama  had  taken  only  thirty-five  minutes.  The 
"sausage,"  which  the  Germans  fired  at  as 
it  came  down  low  over  the  trenches,  landed, 
and  the  French  officers  were  made  prison- 
ei's. 


Memoranda: 


\ 


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The  trenches  and  shell  lioles  and  advancing;  allied  troops  photographed  by  an  allied  aviator. 


How  aero  photofiiaphs  ai<-  put  tci;;.  Iher  to  make  a  continuous  photographic  map.  These  photographs  were  taken  by  Allied 
aviators  at  the  Dardenelles  the  early  part  of  the  war.  The  city  of  Tchanak  and  the  estuary  of  the  Kodja  Chai;  on  the  right  shore 
is  fort  Tchimalik  and  on  tlie  left  fort  Hamidie. 


CHAPTER  VIII 
AERO  PHOTOGRAPHY 


In  the  official  reports  of  military  and  naval 
operations  in  the  present  war  daily  items  can  be 
found  reading  more  or  less  as  follows : 

On  May  20th  the  French  prepared  to  rush  the  im- 
pregnable positions  on  Mount  Cornillet  and  Mount 
Teton.  Photographs  taken  by  their  aviators  showed 
an  immense  system  of  tunnels  which  apparently  con- 
cealed German  reserves.  A  single  entrance  was  lo- 
cated and  the  operator  of  a  French  15-inch  gun  ten 
miles  away  was  told  to  put  a  shell  in  the  entrance. 

The  gun  started  firing  thousand-pound  shells,  and 
the  infantry  was  ordered  to  advance  at  a  certain 
minute.  Two  hours  before  the  time  set  for  the  ad- 
vance a  half-ton  shell  planted  itself  squarely  in  the 
mouth  of  the  tunnel,  killing  half  of  the  men  inside, 
blockading  the  exit,  and  wrecking  the  transverse  cor- 
ridors. The  French  advanced  and  took  several  hun- 
dreds of  prisoners  without  suffering  any  loss. 

Thousands  of  Miles  of  Photographic  Maps 

The  mihtary  and  naval  authorities  of  the 
warring  countries  have  thousands  of  miles  of 
photographic  maps.  These  are  kept  up  to  the 
minute  by  the  constant  stream  of  aerophoto- 
graphs  brought  to  headquarters  by  aviators, 


where  they  are  developed,  studied,  and  the  mi- 
nutest changes  noted  on  the  map. 

The  following  report  gives  an  idea  of  how 
exact  a  science  aerophotography  has  become, 
and  what  its  value  is  in  connection  with  military 
and  naval  operations : 

Several  series  of  photographic  plates,  taken  by 
British  naval  observers  after  the  bombardment  of 
Ostend  by  the  British  forces  on  June  5th,  have 
arrived  at  the  Admiralty  in  London  and  afford  a 
remarkable  example  of  the  development  of  photo- 
graphic observations  and  record  by  aeroplane.  They 
show  in  undeniable  fashion  that  the  British  bombard- 
ment of  Ostend  on  that  date  was  the  most  successful 
thing  of  its  kind  yet  accomplished,  insuring  that 
Ostend  will  be  crippled  as  a  useful  German  base  for 
weeks,  if  not  permanently. 

The  first  series  shows  the  German  base  before  the 
attack,  while  a  second  group  shows  the  effects  of  the 
bombardment.  In  the  pictures  of  the  harbor  one  is 
immediately  struck  by  a  slight  change  in  the  appear- 
ance of  the  great  lock-gates  on  which  all  the  activity 
of  the  harbor  depends.  These  gates  are  100  feet 
long  and  25  feet  high,  and  they  seem  somehow  to 
have  lost  a  little  of  their  rectilinear  character  over- 
night. The  magnifying  glass  reveals  some  of  the 
reasons  for  this  change.     The  breaking  down  of  the 


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One  of  the  large  French  apparatus  for  taking  photographs  from 
aeroplanes. 

locks  prevents  the  retention  of  water  in  the  basin  and 
the  canals  which  feed  it,  incapacitating  the  entire  port 
machinery.  Equally  effective  in  crippling  the  harbor 
is  a  hit  on  the  operating  machinery,  jamming  the 
locks  so  that  ingress  and  egress  is  impossible  until 
elaborate  repairs  are  made. 

The  pictures  confirm  tiie  statement  in  the  official 
communique  that  more  than  half  the  buildings  in  the 
factory  section  of  the  town  have  been  either  destroyed 
or  badly  damaged.  It  is  easy  to  see  that  there  may 
have  been  a  heavy  loss  of  life,  although  the  residential 
section  apparently  was  untouched.  Some  of  the 
ruined  factories  necessarily  operate  night  and  day 
and  many  men  are  employed  at  night  on  the  shipping 
and  docks.     British  shells,  dropped  from  a  height  of 


miles  by  the  high-angle  fire  of  the  British  monitors, 
located  at  a  point  far  below  the  horizon,  frequently 
fell  straight  through  the  roof  of  a  shed  or  factory, 
blowing  out  great  sections  of  the  sides  and  roofs  and 
hurling  a  shrapnel-like  shower  of  splintered  wood, 
steel  and  rock  into  the  adjacent  buildings. 

Twenty  Per  Cent,  of  Aeroplanes  at  the  Front 
Used  for  Aerial  Photography 

Every  military  operation  is  preceded  by  an 
extensive  photographic  survey  of  the  enemy's 
position  and  hundreds  of  photographs  are  taken 
by  the  aero  photographers,  until  headquarters 
has  obtained  all  the  information  necessary  to 
complete  the  photographic  map  upon  which  the 
operation  is  to  be  based. ,  Fully  twenty  per 
cent,  of  the  aeroplanes  used  at  the  different 
fronts  are  employed  in  taking  photographs  of 
the  enemy's  positions. 

For  this  purpose  are  usually  employed  ma- 
chines having  a  speed  of  about  eighty  miles  an 
hour,  and  the  aerophotographer  must  go  down 
as  low  as  jjossible  over  the  enemy's  lines,  with- 
out actually  going  below  the  "safety"  point, 
which  varies  under  different  circumstances. 

When  one  side  has  command  of  the  air,  and 
there  are  plenty  of  fighting  machines  about  to 
keep  the  sky  clear  of  enemy  aeroplanes,  the  task 
of  the  aerophotographer  is  comparatively  easy, 
because  he  only  has  to  contend  with  the  enemy's 
anti-aircraft  guns.  Firing  these  is  not  always 
thought  advisable  by  the  enemy,  as  it  gives  the 
location  and  range  of  the  batteries  to  the  kite 
balloons  and  artillery  aeroplanes  of  the  other 
side.  Till  recently  the  aerophotographer  was 
sent  out  in  a  fairly  slow  aeroplane,  with  a  num- 
ber of  fighting-machines  to  protect  him.  The 
fighting-machines,  flying  at  a  speed  of  about 


1 
i 

■■'^^^          !  ^^''^iSHPiHB?      ^ 

■  ft                                ...      - ,-' .  Ill  m  M\                                                 ''iMSBtBf^^ 

A   French   machine  used   for  pho- 
tography in  1917. 


AERO  PHOTOGRAPHY 


98 


Side  view  of  one  of  the  Farman  aeroplanes  used  for  aerial  photography. 


120  miles  an  hour,  would  fly  around  in  circles 
looking  for  enemy  machines,  while  the  photo- 
graphing-machine went  about  its  business  of 
taking  photographs.  But  oftentimes  a  lonely 
German  aviator,  who  had  taken  his  position  high 
up  in  the  sky  while  waiting  to  dive  on  Allied 
aeroplanes,  in  accordance  with  the  tactics  estab- 
lished by  Immelmann  and  Captain  Boelke, 
would  spy  the  slow  photographing-machine  and 
dive  for  it,  shooting  as  it  drew  near  and  landing 
immediately,  whether  it  brought  down  the  pho- 
tographing-machine or  not. 

In  this  case  the  fighting-machines  which  es- 
corted the  photographing-aeroplane  were  un- 
able to  defend  it,  because  the  battle  was  all  over 
before  they  could  manceuver  to  a  position  which 
would  permit  them  to  intercept  or  fight  the  at- 
tacking German  aeroplane.  As  they  were  fly- 
ing over  German  territory,  they  could  not  fol- 
low the  German  machine  in  its  flight  downward 
over  the  German  lines,  because  of  the  German 
anti-aircraft  batteries. 

This  method  involved  sending  out  from  four 
to  six  machines  to  convoy  a  single  photograph- 
ing-machine, but  did  not  permit  as  good  protec- 
tion as  is  afforded  by  sending  a  larger  photo- 
graphing-machine equipped  with  several  ma- 
chine-guns mounted  forward  and  rear.     These 


permit  the  gunners  of  the  photographing-ma- 
chine to  defend  themselves  against  attacks  from 
even  two  or  three  enemy  aeroplanes.  With  this 
larger  type  of  machine  the  effect  of  an  attack 
does  not  involve  the  loss  of  the  aeroplane,  the 
aviator,  and  the  photographer,  as  in  the  case  of 
the  smaller  machine  which  is  unable  to  defend 
itself.  In  the  former,  if  the  photographer  or 
one  of  the  gunners  is  hit,  the  other  two  members 
of  the  crew  can  keep  up  the  fight  while  flying 
back  to  their  own  lines,  or  until  reinforcements 
arrive.  Therefore  the  tendency  is  toward  the 
employment  of  larger  and  well-armed  aero- 
planes for  aerophotography. 

The  Aerophotographic  Organization  of  an 
Army 

Since  the  value  of  aerophotography  became 
recognized,  the  armies  in  the  field  have  had  spe- 
cial aerophotographic  corps.  The  size  of  these 
corps  has  been  increasing  steadily. 

As  many  of  the  American  aviators  now  being 
trained,  or  to  be  trained,  will  undoubtedly  be 
employed  in  photographic  work,  the  following 
detailed  description  of  the  British  aerophoto- 
graphic organization  will  be  of  great  assistance 
in  giving  the  student  a  comprehensive  pen-pic- 
ture of  this  work. 


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Seven  Aeroplane  Bombs  Photographed  Soon  After  Release  by  the  French  Aviator 

That  Released  Them  on  a  German  Plant 


The  above  is  one  of  the  most  remarkable  snapshots  of  an  aerial  bombardment.  It  Is  an  enlargement  of  a  photoirraph  taken 
by  a  French  aviator  at  a  heipht  of  over  13,000  feet  during  a  raid  on  a  German  nmnitions  jilant  between  Metz  and  Briey,  in  the 
occui)ied  part  of  Ixirraine.  The  bombs  are  shown  the  moment  after  they  were  released  from  the  aeroplane,  and  by  reason  of  the 
persiK-ctive  ajipear  as  if  they  would  fall  in  different  directions  far  from  the  object  aimed  at.  But  the  aviator  has  to  throw  the  bombs 
in  such  a  way  as  to  allow  for  the  fact  that  he  is  traveling  at  a  great  speed  and  for  what  corresponds  to  the  trajectory  of  a  projtx-- 
tile  from  a  cannon.  The  bombs  used  for  aerial  attacks  are  known  as  "M"  (Michelin)  bombs,  and  are  of  two  kinds,  weighing  from 
20  to  100  ]K>unds.  In  this  case  all  the  bombs  were  thrown  together  and  succeeded  in  hitting  their  object,  the  German  munitions 
factory  1h-1ow.  The  district  chosen  for  attack  is  a  great  manufacturing  region  the  Germans  liave  turned  into  a  huge  war  factory. 
The  British  and  French  armies  arc  confining  their  air  raids  exclusively  to  military  ol)jects,  such  as  the  bombing  of  the  sulnnarinc 
establishments  l>ehind  the  German  lines.  Although  we  receive  reports  of  only  the  more  important  aerial  attacks,  these  attacks  are 
of  daily  occurrence,  and  have  caused  far  more  tlamage  than  the  Germans  care  to  admit.    (French  Official  Photo.) 


AERO  PHOTOGRAPHY 


05 


Aeroplane  Photography  That  Shows  Minutest  Details  of  a 
Factory  Chimney  Being  Repaired ! 


M^* 


This  remarkable  photograph  taken  from  a  French  aeroplane  shows  how  the  Allied  aviators  can  fly  low  and  choose  their 
target  in  bombing  German  munition  plants,  provided  there  are  sufficeint  aeroplanes  to  fire  on  and  silence  anti-aircraft  batteries. 
Also  the  clearness  of  the  target  on  an  aerial  photograph  for  use  by  the  artillery. 


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Film-picture  taking  in  mid-air:  a  piiotographer  and  liis  cameri 
in  a  icite-balloon. 


The  prints  are  kept  in  wallets  in  series  b\ 
squadrons,  e.g.,  all  Xo.  25  squadron  prints  from 
2.5  w  1  to  25  w  1000  would  be  kept  in  this  serial 
order  in  probate  wallets. 

Thus  it  is  possible  to  refer  to  photographs  in 
every  way  by  date,  squadrons,  area,  and  so  on. 


Cioiiifi    uj)   ill  a  Ciuqiiul   halliim.   l.»   ..Imcrvc  artillery   firing   in 
France,   and   taking   photos   at  close   range. 


*   ni.   .           L-     nttc        OL     ij  L      c-      -1.  How    scale    varies    with    height,    and    focal 

A  Photographic  Urricer  Should  be   ramihar     i       +1     f  i 
u/:iL  ..u-  c-ii :__  T I •  _i  o__L-  -1-  lengtn  or  lens. 


With  the  Following  Technical  Subjects 


Detection  from  prints  of  bad  work;  differ- 


The  necessarj'  accommodation  for  the  work  at     ^"^^  ^'^^^^^^  S^od  prints  from  poor  negatives, 
present  demanded  from  a  section. 

Apparatus  used — function  of  each  item — ■ 
which  essential  and  which  non-essential.  Rough 
and  ready  substitutes. 

Construction  and  care  of  cameras.  Details 
of  mechanism  and  weaknesses.  Properties  of 
focal  plane  shutter,  and  of  Anastigmatic  lens. 
Function  of  color  filters,  and  Panchromatic 
plates,  advantages,  and  disadvantages.  Causes 
of  failure. 

Attachment  of  cameras  to  machines;  advan- 
tages of  the  various  systems  and  the  reasons. 
Vibration;  results  of  investigations  in  the  field. 


The   Canadian    official    kineniatogniiihrr   gmng    iilmi    in   nn   ob- 
servation balloon. 


AERO  PHOTOGRAPHY 


97 


A  German  Scout  photographed  by  a  French  Scout  early  in  1915  when  aerial  fighting  was  not  in  practice. 


and  poor  prints  from  good  negatives.  Stains, 
and  their  cause  and  cui-e. 

Identification  with  map — this  of  the  first 
importance — recognition  of  roads,  trenches, 
tracks,  wire,  batteries,  etc.  JNIap  square  system 
co-ordinates. 

System  of  central  registry  and  fihng  of  pho- 
tographs. 

Possible  output  of  prints  in  a  given  time. 
Any  section  should,  in  times  of  stress,  be  able 
to  send  out  for  a  week  without  breakdown. 

Time  necessarily  taken  by  the  various 
processes. 

Simple  intelligence  reading  of  photographs. 

Cameras  and  Fittings 

It  is  the  duty  of  the  non-commissioned  officer 
in  charge  of  the  photographic  section  to  see 
that  the  camera  fitting  is  jiroperh"  fixed  to  the 
machine  and  to  place  the  camera  in  it,  adjust 
slit,  clear  lens  from  dust  and  wind  the  tension. 
On  no  account  should  cameras  be  kept  in  the 
hangars. 

Cameras  can  be  taken  from  hot  to  cold,  but 
the  reverse  causes  condensation  to  form  on  lens. 
Care  should  be  taken  to  avoid  this,  or  the  recon- 
naissance will  be  a  failure. 

Loading  of  Plates 

All  plates  should  be  loaded  in  absolute 
darkness,    and    the    metal    sheaths    should    al- 


ways be   cleaned   from  dust   and  rust   before 
loading. 

It  is  advisable  to  load  magazines  as  required, 
and  not  keep  them  loaded,  as  metal  dust  ac- 
cumulates and  particles  of  such  dust  set  up 
chemical  action.  Cameras  should  be  kept  scru- 
pulously free  from  dust,  which  is  one  of  the 
worst  enemies.  Nothing  spoils  the  appearance 
of  a  print  so  much  as  innumerable  pin  holes. 

Negative  Developing 

Discrimination  must  be  shown  not  to  treat 
the  development  of  all  subjects  alike.  A  town 
requires  less  exposure  than  green  fields,  and 
must  be  treated  accordingly. 

Over-development  is  the  usual  fault.  In 
some  countries  with  chalky  soils,  much  detail  is 
lost  unless  great  care  be  shown  in  timing  the 
rate  of  development.  A  thin  negative  with 
plenty  of  detail  printing  through  the  lantern 
in  about  six  seconds  is  about  the  ideal. 

Finish  of  Work 

Work  is  not  allowed  to  stop  on  any  account 
until  all  orders  are  finished. 

All  dishes,  measures,  etc.,  must  be  thoroughly 
cleansed  before  the  men  are  allowed  to  leave. 

Cleanliness  in  the  dark  room  is  essential  to 
efficiency. 


I 


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A  French  photography  twin  motored  biplane. 


I.lnot  of  trenches  on  the  Western  front  photogruj)hcd  from  an  aeroplane.    Soldiers  arc  shown  walking  along  the  trenches. 


I 


AERO  PHOTOGRAPHY 


99 


The  war-kite  in  mid-air. 

A  Squadron  Photographic  Non-Commissioned 

Officer  With  His  Three  Men  Should 

be  Familiar  With  the  Following: 

Details  of  mechanism  of  camera. 

Properties  of  focal  plane  shutter,  and  An- 
astigmatic  lenses. 

Color  filters.     Panchromatic  plates. 

Attachment  of  cameras  to  machines.  Perfect 
fitting  is  essential. 

Care  of  cameras  and  lenses  generally. 

How  to  put  in  a  filter  and  re-lock  the  lens. 

Simple  repairs  to  cameras. 

Jams.  How  they  occiu",  and  how  they  can 
be  avoided. 

Loading  of  magazines  in  complete  darkness. 

Use  of  special  size  plate  and  sheath  gage 
for  loaded  sheaths  to  prevent  jams. 

Formulae  at  present  in  use. 

Development  of 

How  to  obtain  thin,  quick-printing  negatives 
full  of  detail. 

Value  of  "color."  Big  dishes  are  preferable 
to  tanks. 

Cleanliness. 

Washing  and  drying  of  negatives;  use  of 
spirit;  avoidance  of  spirit-fog  due  to  sunshine 
and  change  of  temperatiu-e. 


The  observer  and  photograplier  in  mid-air  supported  by  kites. 

Use  of  hydrochloric  acid  to  take  out  occa- 
sional excess  of  color. 

Printing;  speed  is  essential.  Hand-shading. 
Every  man  should  be  able  to  make  at  least 
good  prints  per  hour. 

Substitutes  for  apparatus.  Gasoline  tanks 
as  fixing  tanks,  etc.  The  excellence  of  old 
doped  fabric  with  which  to  make  big  dishes. 

Development  of  prints.  One  man  should  be 
able  to  develop  at  least  12  prints  at  once,  in 
one  dish  with  one  hand,  and  to  fix  them  in  an- 
other dish  with  the  other  hand. 

Washing:  thoroughness. 

Drying;  spirit  and  burning-off  processes. 

Identification  of  photographs  with  maps. 

Characteristic  natural  and  artificial  features. 

Reversed  writing  for  marking  negatives. 

A  sound  idea  of  the  shutter  slits  and  expo- 
sures to  be  used.  System  of  catalogue,  and 
filing. 

Lantern-plate  and  positive  making  both  on 
sy^  by  31/4  and  by  contact, 

Science  of  Aerophotography  Still  Young 

The  science  of  aerophotography  is  still  in  its 
infancy.  Up  to  the  present  time  it  may  be  said 
that  only  existing  forms  of  cameras,  or  modi- 


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The  Herbert  &  Husgen  multiple  aeroplane  camera. 


fied  cameras,  have  been  used  to  take  aeropho- 
tographs.  Little  has  been  done  to  develop  spe- 
cial photographic  apparatus  to  take  better  pho- 
tographs from  the  air  at  different  altitudes  in 
order  to  show  in  sharper  detail  the  topography 
of  the  country,  either  straight  below  or  in  per- 
spective. 

Essentials  in  Aerophotographs 

The  essential  thing  in  taking  aerophotographs 
is  to  bring  back  a  perfect  record  or  map  of  the 


Four  type*  of  nrroplnne  rnniprns  used  by  tlic  Frencli  Air  Serv- 
ice.   (Official  Phiito,  from  the  Illustratwl   Liindoii  News.) 


surface  below,  with  the  component  objects  in 
their  true  proportions. 

The  military  commander  mainly  wants  to 
know: 

(1)  The  distance  between  points. 

(2)  The  location  of  objects,  such  as  enemy 
batteries,  structures,  trenches,  camps,  roads, 
ridges,  bodies  of  water,  etc. 

(3)  The  disposition,  or  traces  of  movements, 
or  actions  of  the  enemy.  If  a  battery  is  shown, 
it  is  essential  to  know  that  it  is  not  a  dummy 
battery. 

(4)  The  elevation  of  ridges  or  depth  of  de- 
pressions where  his  own  forces  may  hide  in 
advances. 

(5)  The  nature  of  the  country,  whether  it  is 
solid  ground,  marshes,  forests,  cultivated  land, 
brush,  etc. 

To  take  an  accurate  map  of  the  surface  be- 
low and  eliminate  distortions,  the  axis  of  the 
camera  must  be  kejjt  vertical  to  the  gx'ound. 

Relative  Elevations  Hard  to  Show 

Relative  elevations  cannot  be  shown  in  an 
aerophotograph,  except  l)y  contrast,  when  the 
elevation  occurs  near  bodies  of  water,  or  tlic 
photograph  is  taken  close  to  the  ground  or  in 
perspective. 


AERO  PHOTOGRAPHY 


101 


Whenever  airmen  bomb 
places  they  must  bring 
back  photos  showing 
the  damage  done.  As 
the  anti-aircraft  guns 
begin  to  fire  as  soon  as 
the  bombing  plane  is 
detected,  the  aviator 
takes  the  photos  of  the 
damage  as  he  climbs  to 
safe  altitudes.  This 
photo  shows  buildings 
on  fire  after  bombs 
were  dropped. 


In  the  last  case  the  image  is  distorted,  al- 
though, of  course,  the  information  that  it  con- 
veys regarding  elevations  is  invaluable.  But  a 
trained  reader  of  aerophotographs  can  detect 
elevations  in  the  prints,  as  well  as  the  nature 
of  the  surface. 

The  nature  of  the  surface  is  harder  to  detect 
■even  in  ballooning.  Messrs.  Alan  R.  Hawley 
and  Augustus  Post,  during  their  forty-six-hour 
balloon  trip,  which  started  at  St.  Louis  and  ter- 
minated in  the  wilds  of  Canada,  were  deceived 
by  the  look  of  the  country  from  a  height  of 
15,000  feet,  at  which  elevation  they  were  trav- 
eling. It  was  in  October  and  the  leaves  were 
turning  yellow.     The  contrast  of  spots  where 


the  leaves  were  green,  extending  over  miles  of 
country  comprised  in  their  perspective,  led  them 
to  believe  they  were  traveling  over  cultivated 
country,  when  they  were,  in  fact,  traveling  over 
unexplored  country. 

Interpreting  Photographs  Requires  Skill 

Interpreting  or  reading  photographs  requires 
skill  gained  by  long  experience. 

The  expert  "interpreter"  of  photographs 
must  be  able  to  gage  distances  and  elevations 
at  a  glance,  and  also  tell  the  nature  of  the 
surface. 

The  camera  always  flattens  the  field  and  de- 
stroys perspective,  but  the  trained  "interpreter" 


The  pistol-camera  for   German  airmen — the   right   side. 


The  pistol-camera  for  German  airmen — the  left  side. 


102  4 •//;;:: -TEXTBOOK  OF  MILITARY  AERONAUTICS 


Camera  mounted  on  a  British  R,  E.  liiplane,  Major  Campbell  in  the  pilot  seat,  demonstrating  it. 

(Photo  Bureau  of  Public  Information.) 


reaches  a  point  where  he  is  able  to  tell  at  a 
glance  the  nature  of  the  surface  from  a  photo- 
graph. 

Problems  of  Aerophotography 

The  problems  of  aerophotography  resolve 
themselves  into  the  one  big  problem  of  showing 
the  nature  of  the  things  photographed. 


Thr  Ragtman  aeroplane  cnmera. 


The  important  factors  in  aerophotography 
are: 

( 1 )  Tiie  plate.  Experiments  should  be  con- 
ducted to  develop  special  plates,  so  that  lumi- 
nosity, water-vapor,  haze,  and  smoke  can  be 
filtered,  and  good  photographs  taken  under  any 
condition. 

(2)  The  method  of  development. 

(3)  The  lens. 

(4)  The  mechanical  constniction  of  the  cam- 
era and  the  facilities  which  it  may  afford  for 
taking  photographs  in  number,  with  the  records 
of  compass  direction  and  altitude  as  far  as  pos- 
sible. 

(5)  Skill  in  taking  the  photographs.  This 
has  been  elinu'natcd  to  some  extent,  and  it 
should  be  fiirtlicr  cliininated  by  evolving  rules 
which  anybody  can  follow  in  taking  acroplioto- 
graphs.  Skill  in  developing  the  photographs 
and  printing  them  is  another  matter  entirely, 


AERO  PHOTOGRAPHY 


103 


■n<f^ 


The  Fabbri  apparatus  fitted  to  a  fast  scout. 


and  rules  can  never  be  the  equivalent  of  ex-     tograph,  which  may  show  up  with  a  fair  de- 


perience. 

(6)  Edmination  of  vibration.  Vibration  is 
one  of  the  worst  enemies  of  aerophotography. 
It  is  hard  to  eliminate  it  entireh^  and  it  causes 
blurs.  These  decrease  the  clearness  of  the  pho- 
tograph from  ten  to  fifty  per  cent,  although  the 
blurs  are  not  visible  to  the  untrained  eye.  Vi- 
bration is  eliminated  by  mounting  the  camera 
on  special  springs,  or  by  employing  a  gyro- 
scopic device.  Blurs,  due  to  vibration,  destroy 
the  photograph  so  far  as  getting  minute  de- 
tails from  it  are  concerned,  although  when 
looking  at  the  photograph  one  can  recognize 
the  larger  features  of  the  landscape  without 
difficulty.  A  good  photograph  is  like  a  master- 
piece by  Detaille,  so  finely  and  exquisitely 
worked  out  that  it  requires  a  microscope  to  ap- 
preciate the  great  wealth  of  detail  the  artist  has 
put  into  his  work.  On  the  other  hand,  a  blurred 
photograph  may  be  compared  to  a  picture  by 
Claude  ]Monet,  the  great  leader  of  the  impres- 
sionistic school,  in  which  the  salient  objects 
stand  out  clearh'  when  viewed  at  a  little  dis- 
tance, but  become  onlv  splashes  and  daubs  of 
color  when  closely  scrutinized.    A  blurred  pho- 


gree  of  clearness  to  the  naked  eye,  gives  a  con- 
fused image  when  placed  under  a  magnifying 
glass. 


Two    aeroplane    British    Royal    Flying    Corps    cameras 

being  returned  to  headquarters  after  a  flight. 

(Official  Photo.) 


104 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


An  aeropiiotographer  taking  pictures  in  mid-air. 


Efforts  should  be  concentrated  on  developing 
special  plates  which  will  permit  the  screening 
of  luminosity — caused  by  violet  rays  and  pre- 
venting details  from  showing  in  the  photo- 
graph— and  fogs.  There  are,  of  course,  differ- 
ent types  of  fogs, — about  half  a  dozen  kinds, — 
and  some  are  more  difficult  than  others  to  pene- 
trate. On  the  other  hand,  certain  tj^pes  of 
smoke  can  easily  be  penetrated. 

As  a  general  rule,  an  aerophotograph  is  much 
clearer  than  a  photograph  taken  on  the  ground. 
This  is  because  in  photographing  from  the  sky 
there  is  only  a  thin  layer  of  dust  to  penetrate, 
whereas  in  a  photograph  taken  from  the  ground 
the  distance  between  the  camera  and  the  objec- 
tive is  one  continuous  layer  of  dust.  Different 
types  of  cameras  are  used  to  take  aerial  pho- 
tographs, some  intended  to  take  wide  angles 
and  some  to  get  the  details  in  small  areas. 

The  necessit}'  of  photographing  positions 
which  are  well  protected  by  anti-aircraft  guns 
has  necessitated  the  employment  of  cameras. 


DritUh  Naval  Flvlnjf  Corps  stuwinti*  \te\na  Instnu-twl  in  tlu-  handling  of  an  ucropliux-  iim.ra 
•     "^         '  "^  (Official  IMu)to.l 


AERO  PHOTOGRAPHY 


105 


Different  Types  of  Cameras 

Different  types  of  cameras  are  used,  includ- 
ing automatic  cameras,  which  can  take  photo- 
graphs every  ten  or  twenty  seconds. 

As  the  United  States  is  to  supply  many  of 
the  cameras  to  be  used  in  this  war,  it  is  of  in- 
terest to  note  that  several  remarkable  cameras 
are  being  made  in  this  country.  The  newest 
of  these,  a  very  efficient  apparatus,  has  been  de- 
veloped by  the  pioneer  aerophotographer,  Mr. 
J.  F.  Haworth,  M.E.,  of  Pittsburgh.  Al- 
though very  simple  in  construction,  the  camera 
takes  a  surprising  number  of  photographs  per 


minute,  and  also  records  the  speed  of  the  aero- 
plane, as  far  as  it  can  be  estimated,  compass 
directions  and  a  record  of  the  altitude  at  the 
time  the  photograph  was  taken.  Mr.  Haworth 
carried  out  the  photo-cartographic  work  for  Mr. 
Cui'tis,  the  artist,  who  made  the  remarkable 
geological  reproduction  of  the  Kilauea  Vol- 
cano, Hawaii,  which  is  now  in  the  Aggassiz 
Geological  Museum  of  Harvard  University. 
It  was  found  necessary  in  this  work  to  produce 
aerophotographs  with  rapidity,  fidelity,  and 
correct  orientation.  A  special  camera  had  to  be 
devised  for  the  work.     First  of  all,  the  camera- 


Reniarkable  photograph  of  the  Chatnpajrne  trenches  taken  by  a  French  military  observer  during  a  terrific  battle.  It  sliows 
how  the  trenches  are  scientifically  constructed  in  zigzag  formation,  so  that  if  an  enemy  should  capture  them,  it  would  be  impossible 
to  shoot  any  distance  down  them.  The  earth  in  the  Champagne  district  is  of  chalk  formation,  which  outlines  the  trenches  in  white. 
The  pockmarks  in  the  picture  are  where  the  shells  have  exploded. 

'^— ^^'I'app  with  unroofed  houses  in  the  path  of  the  war.  B— Road  worn  by  artillery  and  supply  trains.  C— The  zigzag  con- 
struction of  the  trenches.  D— Pockmarks  where  shells  have  exploded.  E — Connecting  trenches  between  first,  second  and  third  lines. 
F — Ground  between  the  enemy  trenches. 


106 


TEXTBOOK  OF  MILITARY  AEROXAUTICS 


maker  had  to  calculate  the  distance  of  the  geo- 
logical formations  from  a  known  basis.  The 
lava  flow  of  this  volcano  has  an  area  of  six 
square  miles,  and  it  is  rich  in  important  geolog- 
ical formations.  The  work  of  the  camera- 
maker  is  more  exacting,  perhaps,  than  that  of 
the  military  map-maker.  A  camera  was  de- 
vised which  works  automatically  with  its  axis 
vertical  to  the  surface  of  the  earth,  and  has  a 
wide  field  on  either  side.  It  is  necessary  to  take 
successive  pictures  and  correlate  them  by  suc- 
cessive overlapping.  It  was  found  that  the 
magnetic  north  and  south  of  each  picture  and 
the  altitude  facilitated  proper  placing  at  the 
scale  of  the  formation. 


The  camera  now  available  for  aerophotog- 
raphy  remains  unchanged,  except  that  the  time 
of  day  is  now  reported  on  the  photograph. 
This  is  done  automatically  and  the  mechanism 
of  the  camera  can  be  set  to  take  several  pictures 
a  minute.  A  complete  record  of  the  surface 
of  the  earth  beneath  the  aeroplane  may  be  pro- 
cured by  merely  touching  a  lever.  The  camera 
records  the  time  the  aeroplane  goes  over  a  given 
point  in  the  enemy's  country,  the  compass  direc- 
tions, and  the  speed  of  the  aeroplane  as  far  as 
it  can  be  estimated. 

Two  other  remarkable  cameras  suitable  for 
aero-work  have  been  constructed  by  the  Herbert 
&  Huesgen  Co.  of  New  York  and  the  Eastman 


Aero  photo  of  n  liiilitnrv  nrrmlnmic,  "somrwiicre  in  I'rniicr."  sliowiii(j   17   Ihiii  niuliHnl  t  aiiilron   lH|ila]u-.   iiiiil   ;ilioiit   JO  iiiolcn-  trnns- 
|K>rts  Itelonging  to  the  nero  Kqundriin.     The  seven   huge  hungars  ciin   house  about  (iO  aeroplanes. 


AERO  PHOTOGRAPHY 


107 


\ 

4 

«      '"^^^N^. 

■^          '^—"^^      ^s^ffiaEsss^"' 

The  Allies'  command  of  the  air  on  the  western  front,  which  permits  Allies'  airmen  to  map  the  enemy's  trenches. 
A  French  airman  flew  over  the  enemy's  lines  and  brought  back  to  headquarters  in  a  few  minutes  this  perfect  map  of  the  enemy's 

trenches,  with  French  shells  bursting  over  the  trenches. 


Kodak  Co.  The  first  makes  it  possible  to  take 
750  pictures  with  one  loading.  As  a  standard 
size  film  is  used,  it  may  easily  be  projected  on  a 
screen  for  military  purposes. 

The  action  of  the  camera  is  automatic. 
One  pull  of  a  flexible  cable  sets  the  shut- 
ter, makes  the  exposure,  winds  up  the  pre- 
vious exposiu'e  and  registers  the  number  of  pho- 
tographs. It  is  universal  in  focus.  The  lens 
is  exactlj'  the  same  as  that  used  by  professional 
operators  of  motion  picture  cameras,  being  the 
highest  grade  astigmat,  with  a  speed  of  f.4.8. 
It  is  easy  to  operate,  and  the  military  aeropho- 
tographer  can  take  hundreds  of  photographs  of 
important  positions  in  quick  succession  and  yet 
operate  a  gun  to  defend  himself.     This  camera 


weighs  only  6  pounds  and  is  constructed  entirely 
of  metal  and,  therefore,  is  not  easily  broken. 
Altitude  photographs  may  be  taken  with  this 
camera  from  a  height  of  10,000  feet  with  a  lens 
of  special  focal  length,  supplied  with  the  cam- 
era. jVIotion-pictiu'e  films  of  standard  make  are 
used,  which  give  minute  definitions  and  great 
capacity  in  a  small  space. 

Film  vs.  Plate 

On  accoimt  of  its  lightness,  unbreakability, 
and  simplicity,  the  film  is  preferred  for  aerial 
work,  especially  since  there  are  cameras  which 
permit  loading  for  hundreds  of  exposures.  The 
possibility  of  turning  out  films  which  give  as 
good  results  as  plates  is  excellent.    A  great  ad- 


108 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Possible  Troubles  in 

Taking  Aero 

Photographs  and  Their  Remedy 

FaulU. 

Probable  Cause. 

Remedies. 

Plates  fogged. 

leakage. 

Examine  all  screws  on  cone, 
changer  and  lens  plate. 

Open  silt  In  blind  and  place 
an    electric     lamp     Inside 
the  cone  and  examine  for 
light  In  the  dark  room. 

Take    off    changer,    and    fit 
the    magazines    with    lids 
open,    place    a    lamp    In- 
side   the    magazines    and 
examine   for    leakage   be- 
tween       magazine        and 
changer. 

Examine  also  the  magazine 
lld.s. 

Movement       on 

Slit  too  wide. 

Examine  cord,  pulley  plate, 

plates. 

Shutter  sticking. 

teeth  on  "set"  wheel  and 

Bad  fitting  on  machine. 

pinion. 
Examine  blind  and  notice  If 
the  slit  Is  true. 

Negatives   out   ol 

Lens    working    out    of 

Tighten  up,  re-focus,  and  fit 

tociu. 

flange. 

grub    screw. 
Test  with  gage. 

Sheaths    not    dropping 

true       on       changer 

Test  with  sheath  In  gage. 

slide. 

Changer     Jam- 

Changer handle  not  be- 

ming. 

ing    pushed    forward 
to  end  of  movement, 
and  not  allowing  the 
plate    to    drop    clear 
of    the    aperture    In 
changer     slide     Into 

receiving  magazine 

Take    camera    oft    machine. 

Sheaths  being  Inserted 

In  the  wrong  side  of 

and  turn  upside  down,  al- 

the   magazine,    thus 

lowing    sheaths    to    drop 

allowing     the     open 

back     In     the     magazine. 

edge   to   jam   In   the 

Close  lid  In  this  position. 

forward  movement. 

and   re-fit  the  sheaths  In 
their    proper    position    In 
the  magazine. 

Changer    working 

Small    chips    of    glass 

Take  off  top  half  of  changer 

sttn. 

worked  Into  changer. 

and    clean    out ;    oil    run- 
ners. 

Take  oft  top  half  of  changer, 

Changer    handle    bush 

working  loose. 

remove       changer       slide 
plate,  and  tighten  screws 
holding  bush  on  to  plate, 
file    off     any     protruding 
screw     ends     on     reverse 
side. 

Pulley     bracket     slide 

Take    off    inspection    cover 

not  working  freely. 

and  examine. 

Changer      handle 

Shutter     setting     cord 

Release  retainer  screws  and 

not  able  to  fin- 

too tight. 

allow  handle  to  finish  the 

ish      vbole     ol 

forward    movement,    then 

forward    move- 

pull   In    cord    enough    to 

ment. 

give  a  V4.  turn  on  pinion. 

Changer    working 

Cord    retainer    screws 

easily    but    not 

loose. 

setting  ihutter. 

Broken  cord. 

1.  Remove       the       changer 

2.  Take  off   "set"    Indicator 

comer   plate ;    the   pulley 

on     shutter     pinion     will 

now  be  exposed. 

3.  Thread    the    cord    from 

the    Inside   of    the    pulley 

through   the  hole   on   the 

Probable  Cause. 


Changer  working 
easily  but  not 
setting  shutter. 
Continued. 


Releasing  lever 
not  working 
freely. 


Sheath  not  pass- 
ing through 
changer. 

Changer         Jam 
mlng  at  end  of 
forward    stroke 
of   handle. 


Changer  handle 
Jammed  at  re- 
leasing posi- 
tion. 


Broken  cord. 


Camera  being  fitted  on 
outside  of  m/c  and 
having  a  cord  on  re- 
lease lever  which  Is 
exposed  to  the  wind. 
Induces  a  resistance 
which  the  lever  can- 
not overcome. 

Setting  pin  In  pulley 
bracket  slide  broken. 


Changer  Inlet  and  out- 
let being  of  wood 
are  liable  owing  to 
damp  to  swell. 

Changer  slide  plate 
jamming  between 
top  half  of  changer 
and  the  small  stop- 
lips  on  the  end  of 
runners. 

Sheaths  fitted  In  mag 
azlne  wrong  way. 


Remedies. 


roller  side  thereof,  and 
secure  by  means  of  a 
knot.  Wrap  the  cord 
around  the  pulley  five 
times,  first  passing  it  un- 
der and  then  over  the 
groove. 

4.  Thread  end  of  cord 
through  eyeletted  hole  In 
the  corner   plate. 

5.  Replace  corner  plate  and 
changer. 

G.  Pull  cord,  so  as  to  set 
the   shutter. 

7.  Pass  cord  around  sliding 
pulley  on  changer  and 
push  up  changer  slide  as 
far  as  it  will  go.  and  ad- 
just the  cord  to  the  cord 
grip  which  is  attached  to 
the  corner  plate. 

S.  To  Test. — Release  shut- 
ter and  re-set  by  means 
of  the  changer  slide  han- 
dle. If  the  shutter  does 
not  set,  the  cord  is  not 
tight  enough,  and  must  be 
adjusted  by  pulling  a  lit- 
tle further  through  the 
grip. 


N.B. — It  is  very  important 
to  notice  that  while  it  Is 
necessary  to  have  a  cer- 
tain amount  of  tightness 
on  the  cord  In  order  that 
this  shutter  may  set,  it  is 
equally  Important  that 
this  tightness  should  be 
only  just  sufficient  to  set 
the  shutter,  as  other- 
wise, when  working  the 
changer,  the  cord  lt.self 
acts  as  a  stop  for  the 
travel  of  the  changer- 
handle.  Instead  of  the 
handle  slotted  plates. 
The  result  Is  that  the 
cord  will  snap  with  the 
greatest  of  ease.  If  the 
cord  Is  properly  adjusted 
so  that  It  does  not  act 
as  a  stop  to  the  travel  of 
the  changer,  the  cord  will 
last  a  long  time. 

Fit  additional  spring  from 
lever   to   cone. 


Release  cord  from  retainer 
and  take  off  pulley 
bracket  slide  and  re-fit 
pin. 

Test  with  changer  gage  and 
ease  woodwork. 


Bend  the  stop-lips,  UkInK 
care  the  changer  plate 
has  the  full  movement 
forward   when    refitted. 


AERO  PHOTOGRAPHY  109 

vantage  will  be  gained  by  developing  an  effi-  exacting.  Instructions  for  operating  a  camera 
cient  film  to  replate  plates.  The  demands  made  under  these  extraordinary  conditions  are  as 
upon  a  mihtary  aviator  at  the  front  are  very     follows: 


Memoranda: 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


;ular  (hiily   rcionnaissancc  was  ciinductccl  between  Columbus,  X.  ,M.,  and  Colonia  Dublan,  Mcxicd,  tlu-  headquarters  of  General 
Pershing's  punitive  expedition  and  other  points  by  the  first  aero  squadron  during  the  Mexican  trouble. 


CHAPTER  IX 
RECONNAISSANCE  AND  CONTACT  PATROL  WORK  BY  AEROPLANE 


Wellington  said:  "Victory  belongs  to  the 
commander  who  makes  the  best  guess  as  to  what 
is  happening  on  the  other  side  of  the  hill,"  and 
winning  battles  has  always  depended  mainly  on 
quickly  obtaining  accurate  information  concern- 
ing the  enemy. 

Until  the  advent  of  aircraft,  military  opera- 
tions depended  largely  on  skilful  guessing. 
This  guessing  was  made  necessary  by  the  fact 
that  scouts,  whether  mounted  or  on  foot,  could 
only  observe  the  movements  of  a  fraction  of  the 
enemy's  forces,  and  the  length  of  time  required 
for  scouts  to  report  their  observation  was  suf- 
ficient to  permit  the  movement  of  army  corps  in 
an  entirely  different  direction  than  that  re- 
ported. 

Aircraft,  by  permitting  a  scout  to  observe  the 
enemy  from  a  height  where  the  composition  and 
disposition  of  military  forces  can  easily  and 
quickly  be  estimated,  have  removed  the  neces- 
sity of  guessing;  and  by  making  it  possible  for 
air  scouts  to  ti'ansmit  with  a  sixty  to  one  hun- 
dred miles  per  hour  speed  the  movements  of  an 
army  which  can  travel  at  a  rate  of  only  fifteen 
to  twenty  miles  per  day,  they  have  removed  the 
elements  of  surprise. 


Balloons  were  used  for  observation  as  early  as 
1794.  At  the  battle  of  Fleurus,  June  26,  1794, 
the  French  employed  captive  balloons,  and 
thereby  gained  a  decided  advantage  over  the 
Austrians.  Balloons  were  used  in  practically 
every  war  thereafter.  During  the  Franco-Ger- 
man War  of  1870-71,  sixty-six  balloons  were 
sent  up  by  the  French  from  besieged  Paris  be- 
tween September  23,  1870,  and  January  28, 
1871. 

Five  Types  of  Reconnaissance 

Reconnaissance  consists  in  gathering  infor- 
mation from  actual  observation.  The  air  scout 
must  report  facts  and  may  draw  conclusions,  but 
must  not  report  conclusions  instead  of  facts. 

There  are  five  types  of  reconnaissance,  as  fol- 
lows: 

(1)  Distant  reconnaissance,  which  is  essen- 
tially an  examination  of  the  enemy's  country  for 
about  100  miles,  made  for  the  general  staff  for 
strategical  purposes.  This  is  Line  Reconnais- 
sance and  deals  more  with  the  enemy's  general 
location  and  apparent  purpose. 

(2)  Close   Reconnaissance,   which    is   more 


111 


112 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


minute  in  detail  and  extends  about  30  miles  into 
the  enemy's  territoiy.  It  is  more  tactical  and  is 
intended  for  the  use  of  the  local  staff.  This  is 
area  reconnaissance  and  deals  with  the  details  of 
the  enemy's  position  and  defenses. 

(3)  Local  or  artillery  reconnaissance,  which 
is  a  minute  examination  of  the  trenches  and  de- 
fenses. It  is  seldom  more  than  8  or  10  miles  in 
extent. 

(4)  Special  reconnaissance,  which  includes 
obsen-ations  for  artillery  spotting,  locating  new 
targets,  and  other  special  purposes. 

(5)  Contact  patrol  reconnaissance,  which 
aims: 

(a)  To  keep  headquarters  of  formations  in- 
formed as  to  the  progress  of  their  troops  during 
an  attack. 

(b)  To  report  on  the  positions  of  the  enemy 
opposing  the  advance,  the  movements  of  his  im- 
mediate reser\'es,  and  the  state  of  his  defenses. 

( c )  To  transmit  messages  from  the  troops  en- 
gaged to  the  headquarters  of  their  formation. 

Procedure  in  Issuing   Orders   for 
Reconnaissance 

The  following  is  the  normal  procedure  in  issu- 
ing orders  for  reconnaissance : 


Orders  are  issued  by  the  General  Staff  to  the 
wing  commander,  who  in  turn  issues  orders  to 
the  squadron  commander,  who  in  turn  may  issue 
them  to  the  flight  commander. 

The  orders  by  the  general  staff  usually  ex- 
plain the  general  situation  and  so  much  of  the 
commander's  intention  as  it  may  be  necessary 
for  observers  to  know  in  order  that  they  may  un- 
dei-stand  the  objects  of  the  reconnaissance. 

The  information  which  the  commander  re- 
quires is  definitely  stated,  and  the  best  results 
are  obtained  if  the  information  is  asked  for  in 
question  form. 

The  orders  of  the  wing  commander  and  other 
officers  usually  include: 

(a)  Information  as  to  the  enenw  and  of  our 
own  advanced  troops. 

(b)  The  object  of  the  reconnaissance. 

(c)  Route  to  be  followed  if  general  informa- 
tion is  required.  (If  certain  definite  informa- 
tion is  required,  the  route  should  not  be  given.) 

(d)  Special  points  to  be  watched  for. 

(e)  Time  of  starting  if  necessaiy. 

(f)  Method  of  reporting  and  where  to  send 
messages. 

(g)  Procedure  to  be  adopted  in  case  of 
breakdown. 

(h)    What  other  aircraft  are  reconnoitring 


Balloons  were  the  first  type 
of  aircraft  to  be  used  for  ob- 
servation. An  early  artist's 
interpretation  of  the  employ- 
ment of  eaptive  balloons  by 
the  French  at  the  Bafth-  of 
Flcunis,  June  26,  179+.  Being 
thus  su])plied  witli  "aerial 
eyes"  tlie  French  had  tlie  ad- 
vantage over  the  Austrian  ar- 
mies. 


RECONNAISSANCE  AND  CONTACT  PATROL  WORK  - 


113 


The  change  forced  by  aerial  observers.  This 
shows  a  lieavy  French  gun  in  1914^15.  It  was 
not  protected  from  the  aerial  eyes. 


the  same  objective  or  on  the  flanks  of  the  route 
detailed. 

(i)  Number  and  type  of  fighting  aeroplanes 
assigned  to  guard  and  protect  the  observer,  if 
any  are  so  assigned. 

All  orders  and  instructions  should  be  in  writ- 
mg,  except  in  very  special  circumstances. 
They  must  be  given  as  early  as  possible  in  order 
to  allow  the  pilots  time  to  study  their  course, 
plot  compass  bearings,  etc. 

Squadron  and  detached  flight  commanders 
keep  a  record  of  the  general  situation,  so  as  to 
enable  them  to  give  pilots  any  information  they 
may  require  before  starting  on  a  reconnaissance. 
The  best  method  of  keeping  this  record  is  by 
means  of  maps  marked  with  colored  flags. 


Full  information  as  to  the  general  situation 
should  be  given  to  the  pilots  and  observers,  and 
they  should  study  the  map  kept  up  by  the 
squadron  commander  in  order  that,  in  the  event 
of  their  discovering  some  unexpected  informa- 
tion, they  may  be  able  to  decide  whether  it  is  of 
such  importance  as  to  justify  them  giving  up 
their  original  mission  and  returning  at  once. 
As  a  general  rule,  however,  when  an  aircraft  is 
given  a  definite  route  to  follow  or  a  definite  ob- 
jective to  discover,  it  must  complete  its  mission. 

General  information  of  importance  regarding 
procedure,  signaling  map  used  by  observers, 
etc.,  can  be  found  in  the  chapters  on  "Directing 
Artillery  Fire"  and  "Areas  Photography." 
Detailed  information  regarding  scientific  instru- 


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This  shows  a  heavy  French  gun  in  1917,  pro- 
tected from  the  aerial  eyes  by  a  cover  of  cloth, 
branches  of  trees,  and  other  devices  that  are 
part  of  the  art  of  camouflage. 


114 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


A  dummy  gun  half  hidden  by  trees  to  mislead  the  enemy   aerial  observers. 


ments  can  be  found  in  the  "Textbook  of  Naval 
Aeronautics,"  also  published  by  the  Century 
Co.,  X.  Y. 

How    Reconnaissance    Aeroplanes    Are 
Guarded  and  Protected 

•  The  protection  afforded  the  pilots  and  ob- 
server is  naturally  of  great  importance.  The 
danger  to  the  reconnaissance  machines  comes 
from:  (l)  Attacks  by  enemy  fighting  aero- 
planes, (2)  Anti-aircraft  guns.  Against  the 
latter  aviators  can  only  protect  themselves  by 
gaining  information  of  their  location  whenever 
possible  from  other  aviators,  and  by  manoeuver- 
ing  their  airoplanes  to  dodge  shots.  Against 
the  former  there  are  two  methods  of  protection : 
(1)  By  using  larger  and  more  powerful  aero- 
planes, capable  of  carrying  two  or  three  men 
and  from  two  to  four  guns,  thereby  permitting 
each  aeroplane  to  defend  itself ;  (2)  By  sending 
with  the  reconnaissance  patrol  a  guard  of  fight- 
ing machines  to  protect  them  from  attacks. 

The  former  is  becoming  more  and  more  popu- 
lar, because  it  makes  every  aeroplane  self-pro- 
tecting and  eliminates  the  possibility  of  recon- 
naissance aeroplanes  being  brought  down  by  a 
lonely  enemy  machine  which  can  dive  down  on  a 
helpless  reconnaissance  machine,  shoot  the  pilot, 
and  land  before  the  protecting  machines  can  act. 


As  the  fight  takes  place  over  the  enemy's  lines, 
the  fighting  machines  cannot  follow  the  enemy 
machines  in  their  downward  flight  without  ex- 
posing themselves  to  the  fire  of  the  anti-aircraft 
guns.  Three  men  in  a  machine  equipped  with 
dual  controls  and  several  guns  can  withstand 
the  attack  of  any  machine  or  of  several  ma- 
chines, and  one  of  the  three  is  usually  able  to  fly 
the  machine  back  to  his  line,  whereas  in  a  single 
or  two-passenger  machine  the  loss  of  one  man 
often  leads  to  the  loss  of  the  other  man  and  the 
machine. 

The  first  duty  of  the  fighting  reconnaissance 
machines  is  to  gain  information  and  get  back 
with  it.  They  do  not  go  out  with  the  intent  to 
fight,  but  must  be  capable  of  doing  so,  since 
fighting  is  often  necessary  to  enable  them  to 
obtain  the  required  information.  With  two- 
seaters,  the  pilot  operates  the  machine  and  the 
observer  carries  out  the  reconnaissance,  and  both 
operate  the  guns  if  necessary.  In  three-seaters 
the  pilot  operates  the  machine,  the  observer  car- 
ries out  the  reconnaissance,  and  the  third  man 
watches  for  enemy  machines.  It  is  best  for  all 
three  to  know  how  to  pilot  the  machine  and  op- 
erate the  guns. 

Reconnaissance  machines  are  seldom  called 
upon  to  act  alone,  but  fly  in  formation,  one  or 
more  machines  carrying  out  the  reconnaissance, 
while  the  remainder  act  as  escort,  on  the  same 


RECONNAISSANCE  AND  CONTACT  PATROL  WORK 


115 


principle  as  an  escort  on  the  ground.  That  is  to 
say,  they  do  not  seek  an  engagement,  but  fight  if 
necessary,  to  enable  the  reconnaissance  machines 
to  do  their  work.  See  chapter  on  "Fighting 
Planes  and  Aircraft  Guns." 

Protecting  Reconnaissance  Machines 

In  protecting  reconnaissance  machines  from 
attacks,  important  use  may  be  made  of  the  di- 
rections which  have  been  supplied  to  the  person- 
nel of  reconnaissance  machines  of  different  coun- 
tries. These  directions  have  been  found  on  cap- 
tured flight  commanders  or  pilots,  and  should 
therefore  be  carefully  examined  by  students. 

In  reconnaissance,  the  whole  object  is  to  pro- 
tect the  reconnaissance  machine  or  machines,  and 
enable  them  to  complete  their  work.  Opposi- 
tion will  usually  take  one  of  two  forms.  The 
enemy's  scouts  may  employ  guerilla  tactics, 
hanging  on  the  flanks  and  rear  of  the  formation, 
ready  to  cut  off  stragglers,  or  attacking  from 
several  directions  simultaneously,  or  else  the 
formation  may  be  attacked  by  a  hostile  forma- 
tion. A  suitable  type  of  two-seater  fighting 
reconnaissance  machine  will  often  be  able  to 


deal  with  either  class  of  opposition  without  as- 
sistance. The  machines  must  fly  in  close  for- 
mation, keep  off  enemy  scouts  which  employ 
guerilla  tactics  by  long-range  fire,  and  be  ready 
to  attack  a  hostile  formation,  if  the  enemy's 
opposition  takes  that  form. 

Reconnaissance  formations,  like  fighting  for- 
mations, can  be  organized  in  groups,  each  with 
its  sub-leader,  but  as  the  object  is  to  secure  the 
safety  of  the  reconnaissance  machine,  the  whole 
formation  must  keep  together  and  act  as  one. 

If  scouts  are  used  in  combination  with  two- 
seater  machines  on  a  reconnaissance,  it  is  usually 
preferable  to  keep  the  two  types  of  machines 
as  distinct  formations,  each  under  a  separate 
leader.  The  two-seaters  act  as  described,  and 
the  scouts  fly  above  them  in  such  a  position 
as  to  obtain  the  best  view  of  them  and  the  great- 
est freedom  of  manoeuver  in  any  direction. 
Their  role  is : 

( 1 )  To  break  up  an  opposing  formation. 

( 2 )  To  prevent  the  concentration  of  superior 
force  on  any  part  of  the  reconnaissance  forma- 
tion. 

(3)  To  assist  any  machine  which  loses  forma- 
tion through  engine  or  any  other  trouble. 


A   fake   battery   planted   to  deceive   the   aerial   observer. 


k 


116 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Gothu  bombing  acroi)lane  brought  down  in  Belgium  while  returning  from  u  rail  un  Englcuul. 


Navigation  Rules  for  Reconnaissance 

The  height  at  which  aircraft  will  fly  during 
reconnaissance  is  governed  by  the  state  of  the 
atmosphere  and  the  consequent  ease  of  observa- 
tion. The  duty  of  gaining  information  must  be 
the  primary  consideration,  and  aircraft  person- 
nel must  always  be  prepared  to  expose  them- 
selves to  hostile  fire  if  they  cannot  otherwise 
carry  out  efficient  obsen^ation. 

The  difficulty  of  replacing  trained  personnel 
and  aeronautical  material  must,  however,  always 
be  borne  in  mind. 


Shells  of  the  big  guns  hiildtn   trmn  the  aerial  observer's  eyes. 


Once  obtained,  information  must  he  delivered 
at  headquarters  as  safely  and  rapidly  as  pos- 
sible. Consequently,  aircraft  retin-ning  from 
reconnaissances  should  fly  at  such  a  height  as  to 
render  them  absolutely  immune  from  fire  from 
the  ground. 

The  chances  of  being  hit  from  the  ground  will 
be  diminished  by  following  an  imeven  course 
both  in  direction  and  elevation.  Advantage 
may  also  be  taken  of  cloud  for  concealment. 

The  action  to  be  taken  against  hostile  aircraft 
will  vary  according  to  the  mission  which  the 
pilot  has  been  given. 

Should  he  have  been  despatched  to  clear  up 
some  important  point,  or  should  he  be  retm-n- 
ing  with  valuable  information,  he  must  be  care- 
ful to  concentrate  his  energies  on  avoiding  hos- 
tile aircraft. 

If,  on  the  other  hand,  having  seen  nothing,  he 
should  neet  a  hostile  aircraft  over  or  near  a 
place  where  it  is  obvious  that  it  must  have 
gained  valuable  information,  he  must  attack  it. 

It  must  be  borne  in  mind  that  the  side  whose 
aircraft  show  the  greater  determination  to  fight 
on  every  opportimity  Avill  rapidly  gain  a  moral 
ascendancy  which  will  largely  contribute  to  ob- 
taining the  command  of  the  air. 

Pilots  and  Observers 

In  order  that  good  results  may  be  obtained 
from  aerial  reconnaissance,  the  same  |)ilot 
and  observer  should  Avork  together  as  far  as 
possible.  Mutual  confidence  is  of  the  utmost 
importance. 

It  has  been  found  inadvisable  to  lav  down  any 


RECONNAISSANCE  AND  CONTACT  PATROL  WORK 


117 


rules  as  to  the  respective  duties  of  pilots  and  ob- 
servers. These  must  depend  largely  upon  the 
personality  and  air  experience  of  the  indi- 
viduals. On  receipt  of  orders,  the  pilot  and  ob- 
server should  consult  together  with  the  aid  of  a 
map  as  to  the  best  manner  of  fulfilling  their  task 
and  the  route  to  be  followed. 

Compass  bearings,  distances,  and  times  must 
be  worked  out,  and,  if  necessary,  tabulated  and 
fixed  to  the  machine,  so  as  to  be  clearly  visible 
during  flight.  Allowance  must  be  made  for  the 
probable  drift  due  to  the  wind  at  the  height  at 
which  the  aeroplane  will  fly. 

The  pilot  is  responsible  that  his  machine,  if  in 
flying  order,  is  ready  to  go  up  whenever  re- 
quired. Before  starting,  he  must  test  his  en- 
gine, verify  the  quantity  of  oil  and  petrol  in  his 
tanks,  and  make  a  final  inspection  of  the  ma- 
chine with  his  mechanics. 

He  marks  the  route  on  his  map  and  places  it 
in  readiness. 

The  observer  also  marks  his  map,  and  in  cer- 
tain cases,  when  a  detailed  reconnaissance  is  re- 
quired, makes  an  enlargement  of  it  and  dupli- 
cates it  with  the  aid  of  carbon  paper.  He  pre- 
pares his  apparatus,  notebook  or  writing  block, 
pencils,  weighted  message  bags,  watch,  field- 
glasses  and,  in  some  cases,  a  camera. 

No  person  going  up  in  an  aircraft  should 
carry  written  matter  or  maps  which,  in  the  event 
of  an  accident,  would  be  found  on  him  and  give 
information  to  the  enemy. 

The  responsibility  of  finding  the  way  must  be 
shared  by  the  pilot  and  the  observer;  the  actual 
method  of  navigation  adopted  depends  on  the 
nature  of  the  country,  the  state  of  the  weather, 
and  the  type  of  aeroplane  used. 

The  pilot  will  conform  to  the  direction  of  the 
observer  as  regards  moving  slightly  to  right  or 
left,  so  as  to  gain  a  clearer  view  of  a  road,  cir- 
cling round  so  as  to  examine  a  place  more  thor- 
oughly, or  coming  lower  down  to  get  a  clearer 
view. 

The  pilot  should  assist  in  observation  by  look- 
ing out  on  the  opposite  side  to  the  observer. 

Observers  must  be  constantly  on  the  look  out 
for  information  both  on  the  way  out  or  returning 
from  their  reconnaissance ;  and,  though  they  may 
have  accomplished  the  tasks  specifically  allotted 


To  deceive  the  aerial  enemy's  observers  the  art  of  camouflage 
is  applied  to  men  as  well  as  machines-  The  crew  of  a  French 
antiaircraft  gun  dressed  with  a  view  to  invisibility. 

to  them,  they  must  not  consider  their  duty 
finished. 

In  addition  to  using  a  speaking  tube,  a  simple 
code  of  signals  should  be  arranged  so  that  the 
observer  can  communicate  his  wishes  to  the  pilot 
without  the  latter  having  to  switch  off  or  throttle 
down  his  engine. 

In  the  case  of  a  forced  landing  inside  the 
enemy's  lines,  when  it  is  evident  that  the  machine 
must  be  captured,  the  pilot  is  responsible  for 
taking  such  steps  as  will  render  it  useless  to  the 
enemy;  setting  fire  to  it  will  generally  be  the 
most  effective  method. 

The  pilot  will  assist  the  observer  in  making 
out  his  report.  All  reports  will  be  signed  by  the 
observer. 

Messages  should  be  written  out  fully  in  the 
recognized  manner,  headings  being  as  far  as 
possible  filled  in  before  leaving  the  ground.  It 
must  be  remembered  that  the  omission  of  any  of 
the  usual  headings  will  reduce  the  value  of  a  re- 
port or  may  even  render  it  useless. 

The  positions  of  troops  on  the  ground,  espe- 
ciallj^  when  they  are  scattered,  can  often  be  most 
easily  explained  by  showing  them  on  a  carbon 
tracing  or  enlargement  of  the  map.  A  rough 
diagram  will  frequently  be  of  great  value  in 


118 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


■uiwi  I. .  J  immmimim 


i!xm>fiim<mam^.''»it-:m!9!?MVi^''' 


Directing  a  movement  of  troops  by  aeroplane. 


elucidating  the  exact  meaning  of  a  written 
message. 

Facts  only  are  to  be  reported ;  it  is  the  duty  of 
the  staff  to  which  the  report  is  sent  to  make  the 
deductions.  For  instance,  the  positions  of  the 
head  and  tail  of  a  column  at  given  times  should 
be  stated  and  not  merely  its  deduced  strength. 

An  observer  will  always  report  if  he  is  in  any 


The  Sopwlth  tractor  biplane,  widely  used  in  tlic  war  w>ne. 


doubt  regarding  the  reliability  of  his  observa- 
tions. 

In  cases  when  an  aircraft  has  been  out  for 
some  hours  and  seen  a  number  of  small  details, 
it  is  advisable  to  add  the  general  impression 
formed  by  the  observer  as  a  result  of  what  he  has 
seen,  but  it  must  be  made  quite  clear  that  this  is 
merely  an  opinion  and  not  necessarily  a  fact. 

It  is  of  great  importance  that  reports  from 
aerial  observers  should  reach  their  destination  as 
soon  as  possible.  INIuch  of  the  value  of  aerial 
reconnaissance  will  be  lost  if  the  information  so 
quickly  gained  is  delayed  in  transmission  to 
headquarters. 

Aircraft  Report  Diary 

An  aircraft  report  diary  should  be  kept  in 
each  scpiadron  or  detaclicd  fliglit. 

A    summary    of    the    information    collected 


IIECONNAISSANCE  AND  CONTACT  PATROL  WORK 


119 


A   Russian  air  scout  operating  under  difficult  conditions. 

should  be  made  out  daily  and  sent  to  the  head- 
quarters concerned,  to  prevent  the  possibility  of 
any  message  having  been  overlooked  or  having 
gone  astray  without  the  knowledge  of  those 
concerned. 


Contact  Patrol    (Aeroplanes  De  Liason) 

The  contact  patrol,  which  came  in  the  year 
1916,  is  one  of  the  latest  developments  in  mih- 
tary  science.  Established  at  first  as  a  con- 
venience, it  is  now  a  distinct  service  of  extraor- 
dinary importance,  and  binds  together  the  aerial 
and  land  forces. 

As  a  writer  pointed  out  in  Aerial  Age 
Weekly  recently,  Contact  Patrol,  which  is  one 
of  the  chief  raisons  d'etre  of  the  aeroplane,  is  a 
special  tactical  reconnaissance  carried  out  dur- 
ing the  progress  of  an  attack.  It  establishes  a 
liaison  between  the  front  line  infantry  and  their 
battalion  headquarters,  corps,  or  division  head- 
quarters in  the  rear.  The  aeroplane  is  the  most 
valuable  means  of  connection,  and  accomplishes 
the  following  objects: 


(a  nnderwood  &,  Underwood 
Remarkable  photo  of  a  French  Spad  Chaser  plane,  taken  from  above,  under  great  difficulties. 


120 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


r 


One  of  the  Hrrjfuct  homWmii  tyiM-  bipliinrs  used  by  the  French,  which  arc  most  rcinarkuble  clhiibers,  thouL'h  they  arc  limited  in  the 
load  they  ean  carry.    I'nfortunately  the  Germans  have  hroiiirht   down   several   of   this    tyi>c   and    will    be   able   to   copy    it. 

(French  Official   Photo.) 


RECONNAISSANCE  AND  CONTACT  PATROL  WORK 


121 


A  Farraan  reconnaissance  biplane  passing  another  reconnaissance 
machine. 

1.  Keeps  higher  command  informed  of  own 
troops'  movements. 

2.  Keeps  higher  command  informed  of  en- 
emy troop  movements. 

3.  Carries  messages  from  battahon  headquar- 
ters to  corps  and  division  headquarters. 

4.  Reports  the  state  of  enemy  trenches  dur- 
ing an  attack,  and  also  reports  any  new  enemy 
trenches. 

There  are  four  methods  of  signaling  from 
the  ground  to  an  aeroplane  engaged  in  contact 
patrol.    They  are: 

1.  Ground  strips.  This  method  consists  in 
white  strips  of  cloth  which  are  placed  on  the 
ground  in  various  shapes  according  to  prear- 
ranged code.  Thus,  a  ground  strip  in  the  shape 
of  a  "T"  might  mean  "Need  Ammunition,"  or 
some  similar  message. 

2.  Signal  Lamps.  These  are  colored  lamps 
with  a  special  slide  which  pennits  light  to  ap- 
pear in  flashes,  long  and  short,  and  the  mes- 
sages are  sent  according  to  the  Morse  Code,  or 
some  other  prearranged  code. 

3.  The  Shutter.  The  shutter  is  a  device  very 
similar  to  the  ordinary  window  bhnd,  with  one 
side  of  each  shutter  painted  white  and  the  other 
side  black.  It  is  operated  by  a  cord,  and  the 
code  used  is  generally  the  INIorse  International. 

4.  Flares.  These,  as  the  name  suggests,  are 
simply  oil-soaked  cloths  which  are  lighted  by  the 
front  line  troops  to  show  their  position  during 
the  attack. 


On  sunny  days  the  method  most  used  is  the 
panel,  but  on  dull  days  the  lamp  is  used.  Gen- 
erally an  infantry  battalion  has  either  the  lamp 
or  the  panel  (Shutter),  sometimes  both.  The 
battalion  headquarters  always  has  both.  All 
messages  are  sent  from  battalion  headquarters. 

The  following  are  the  methods  used  by  the 
aeroplane  to  communicate  with  headquarters: 
1.  Wireless.  2.  Signaling  Lamp.  3.  Klaxon 
Horn.  4.  Skeleton  maps,  and  messages 
dropped  in  weighted  message  bags.  In  some 
brigades,  by  Very's  lights  and  smoke  bombs. 
In  the  Very's  light  method  a  red  and  green 
flare  are  used,  and  the  succession  in  which  they 
are  fired  indicates  the  message.  Wireless  is 
very  rarely  used  in  contact  patrol  work,  and  is 
never  used  to  refer  to  the  position  of  our  own 
troops,  as  the  code  might  be  intercepted  by  the 
enemy  very  easily. 

As  our  own  barrage  fire  is  regulated  by  the 
aeroplanes  on  contact  patrol,  the  pilot  of  the 
aeroplane  must  be  absolutely  certain  that  the 
troops  signaling  they  are  the  first  line  are  the 
first  line,  as  a  mistake  would  place  them  di- 
rectly vmder  their  own  barrage  from  the  rear. 
Thus  in  very  doubtful  cases  the  aeroplane  flies 
so  low  that  the  pilot  recognizes  the  uniforms  of 
our  own  troops.     This,  of  course,  makes  the 


A  "protecting"  Xieuport  fighting  biplane  photographed  by  the 
observer  of  a  reconnaissance   machine. 


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A  two  seater  Morane-Laulnier  contact  patrol   machine. 


work  very  dangerous.  The  procedure  of  con- 
tact patrol  work  during  an  attack  is  as  follows : 
The  hour  for  the  attack  is  known  as  the  "Zero 
Hour,"  and  all  watches  and  time  pieces  are  care- 
fully set  to  coincide  to  the  second.  Exactly 
at  the  Zero  Hour  the  aeroplane  must  arrive  over 
the  front  line  trenches,  in  such  a  position  to  be 
over,  or  imder  the  expected  barrage,  generally 
just  over  it,  at  a  height  of  1500  to  2500  feet. 
The  pilot  watches  the  attack  until  the  infantry 


reaches  its  first  objective,  then  signals  "Where 
are  you?"  by  one  of  the  methods  described 
above.  The  infantry,  in  response,  lights  a  flare 
to  show  their  position,  and  the  pilot  traces  it  on 
a  skeleton  map,  and  flies  directly  back  to  head- 
quarters. Arriving  at  this  position,  he  places 
the  map  in  a  weighted  message  bag,  together 
with  any  other  message  he  wishes  to  send,  and, 
coming  down  to  an  altitude  of  about  200  feet, 
drops  the  bag.    If  the  ground  does  not  acknowl- 


1 

. ^^  1 

P 

>i^K  ^^>flHK;  i4|H 

1                     -     ll>>^ii.i.^ 

■iB^Bii 

An  Allii-d  /,c|i|)flin  <liii»i-r  wliirh  <iirrii-s  a  timclimi-  (.niii   iiiiiiiiilrd  ill   fridit  of  lilt-  car,  anil   alta<ln(l  to  Oir   frame  work  arc  a  iicrics 
of  ruclcctH,  and  Ix-low  tho  lower  wings  a  battery  of  searchlights.     Note  the  rockets  for  setting  Zejipelins  on  Are. 


RECONNAISSANCE  AND  CONTACT  PATROL  WORK 


128 


A  squa 


c;ioii   ui 


N  .c 


edge  the  message  in  two  minutes,  he  drops  an- 
other, and  keeps  this  up  until  his  message  is 
received  and  acknowledged. 

An  example  of  the  great  covu-age  often  dis- 
played in  this  branch  of  work  was  shown  during 
an  attack  on  Dead  JNIan's  Hill  bv  the  French 


)iUn  used  for  special  contact  patrol  work. 

Infantry.  As  is  well  known,  this  hill  has  passed 
back  and  forth  many  times,  and  some  of  the 
fiercest  fighting  of  the  war  has  taken  place  on 
its  slopes.  During  this  particular  attack  the 
pilot  of  the  aeroplane  engaged  on  contact  pa- 
trol wished  to  make  no  mistake,  so,  descending 


French  pursuit  machine  being  prepared  for  a  flight  over  the  enemy's  lines.     (French  official  photo.) 


124 


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under  his  own  barrage,  to  a  height  of  about 
100  feet,  he  flew  directly  over  the  heads  of  his 
own  troop,  and  hterally  climbed  the  hill  with 
them! 

Contact  patrol  is  thought  to  be  the  most  dan- 
gerous of  all  the  various  usages  of  the  aeroplane 
at  the  front,  and  requires  a  man  not  only  of 
unquestioned  courage,  but  of  great  judgment. 
It  is  the  connecting  link  between  the  man  in  the 
trench  and  the  man  directing  the  attack,  and  as 
such  must  at  all  times  give  accurate  informa- 
tion, as  one  mistake  may  mean  the  loss  of  thou- 
sands of  hves.     It  is  a  work  without  the  glory 


of  the  aerial  fighter  in  his  scout  machine,  miles 
above  the  earth,  but  is  vitally  important  to  the 
success  of  an  attack.  In  an  attack,  in  addition 
to  doing  his  work,  the  pilot  has  five  forces  to 
contend  with.  They  are:  His  own  barrage,  the 
enemy's  barrage,  anti-aircraft  guns,  enemy  ma- 
chine guns,  and  enemy  aeroplanes.  Thus  it  can 
be  seen  that  a  pilot  who  flies  up  and  down  the 
lines  in  a  straight  line  invites  destruction.  So 
the  pilot  must  know  the  trajectory  of  the  heavy 
guns  being  used  in  the  barrage,  so  as  to  keep 
above  or  below  it,  he  must  never  fly  in  straight 
lines,  or  continue  always  at  the  same  speed. 


Memoranda: 


A  patrolling  French  aeroplane  signalinfr  with  searchlight  above  darkened  Paris.     This  remarkable  photograph  was  taken  from  the 
Church   St.  Gervais  looking  toward   Notre  Dame  (on  the  right)  and  the  Pantheon  (on  the  left). 


CHAPTER  X 
NIGHT  FLYING 


Since  practically  all  offensive  aeronautic 
work  is  now  done  under  cover  of  darkness  night 
flying  is  one  of  the  essential  things  an  aviator 
must  learn. 

Zeppelin  Raids  Forced  Aeroplane  Night 
Flying 

The  night  Zeppelin  raids  forced  aeroplane 
night  flying  on  a  large  scale.  The  Allies  were 
forced  to  establish  night  aeroplane  patrols  by 
public  opinion,  which  seemed  to  take  for 
granted  that  a  few  aeroplanes  in  the  sky  would 
be  able  to  prevent  Zeppelins  from  cariying  out 
their  work  of  destruction.  Public  demand  had 
to  be  met,  notwithstanding  the  fact  that  no  one 
coidd  say  just  how  the  aviators  were  to  go  up 
at  night,  whether  they  could  see  other  aircraft 
traveling  in  the  dark  sky,  how  they  could  main- 
tain their  machines  on  an  even  keel,  how  they 
were  to  return  to  their  starting-place  and  land 
against  the  wind,  etc. 

Long-Distance  Bombing  Night  Raids 

Long-distance  bombing  raids  are  conducted 
entirely  at  night.  During  the  day  the  anti- 
aircraft guns  and  enemy  aeroplanes  combine  in 


125 


preventing  successful  results.  At  night  neither 
the  anti-aircraft  guns  nor  the  aeroplanes  are  ef- 
fective. With  few  exceptions,  therefore,  raids 
are  conducted  at  night,  unless  there  are  trains 
loaded  with  troops  or  supplies  to  be  destroyed, 
or  something  of  a  pressing  nature  to  be  bombed. 

Aeroplanes  Cannot  Be  Seen  One  Hundred 
Feet  Away 

At  night  aeroplanes  cannot  be  seen  one 
hundred  feet  away,  and  it  is  difficult  for  the 
searchlights  to  "pick  them  up."  Dirigibles  can 
be  picked  up  with  comparative  ease.  The  in- 
visibility of  aeroplanes  at  night  is  illustrated  by 
an  experience  at  Salonika.  An  Allied  aero- 
squadron  started  out  one  night  to  bomb  the 
Turkish-German  positions.  On  arriving  at  a 
point  above  the  German  lines  the  bombing 
party  was  surprised  to  see  the  Germans  light  up 
their  aerodrome.  They  took  advantage  of  the 
opportunity  and  dropped  their  bombs  on  the 
hangars  and  other  buildings.  When  they  re- 
turned to  their  own  lines  they  found  that  the 
Germans  had  meanwhile  bombed  the  Allies' 
aerodromes.  Both  forces  had  planned  bomb- 
ing raids  at  the  same  time  to  surprise  the  other 
side.     The    bombing    squadrons    passed    each 


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A  Zeppelin  over  London  at  night. 


other  on  the  way,  but  without  observing  one  an- 
other. In  each  case  the  officers  in  charge  of  the 
aerodromes,  upon  hearing  the  noise  of  aero- 
plane motors,  thought  it  was  the  noise  of  their 
own  aircraft  returning  and  lit  up  their  aero- 
drome to  enable  them  to  land. 

The  Operation  of  Aeroplanes  by  Night 

While  the  navigation  of  airships  by  night  is 
a  comparatively  simple  matter,  such  is  not  the 
case  with  the  aeroplane,  which  cannot  stop  in 
mid-air  for  the  purpose  of  inspecting  the  ground 
beneath.  And,  whereas  an  aeroplane  lands 
with  a  velocity  of  seldom  less  than  forty  miles 
per  hour,  it  is  imperative,  if  aeroplanes  are  re- 
quired to  fly  by  night,  to  provide  adequate  land- 
ing and  navigating  facilities. 

First,  the  aviator  must  know  his  relative  posi- 


tion to  the  ground.  For  this  purpose  the  ma- 
chine must  be  fitted  with  an  altimeter,  for  indi- 
cating the  height,  an  inclinometer  for  indicat- 
ing the  aeroplane's  inclination,  and  finally,  posi- 
tion lights  showing  the  transverse  position  of  the 
wings.  The  latter  requirement  is  attained  by 
small  electric  bulbs  (colored  blue  so  as  not  to 
blind  the  pilot  nor  reveal  his  presence  to  the 
enemy)  which  are  fixed  on  both  wing-tips;  the 
current  is  furnished  by  a  storage  battery,  which 
is  also  used  for  lighting  the  blue  lam})s  which 
permit  reading  the  navigating  instruments. 

The  same  battery  may,  furthermore,  be  used 
for  working  a  small  searchlight,  with  the  help 
of  which  the  pilot  might  hope  to  effect  a  land- 
ing if  forced  down  by  engine  trouble.  The  use 
of  searchlights,  however,  has  not  been  general 
on  aeroplanes.     Since  it  might  reveal  the  avia- 


NIGHT  FLYING 


127 


French  aviator  about  to  start  on  "Zeppelin  Duty"  at  niglit,  the  searchhght  being  temporarily  turned  on  the  machine. 


tor's  presence  to  the  enemy,  it  is  now  used  ex- 
tensively for  landings. 

The  second  and  principal  requirement  for 
night  flying — assuming  the  engine  to  be  of  a 
reliable  kind — consists  in  providing  adequately 
lighted  landing-stations. 

Lighting  the  Aerodromes 

The  principle  governing  the  lighting  of  aero- 
dromes for  night  landing  consists  in  suppressing 
all  light  that  might  bhnd  the  aviator,  and  only 
using  such  as  will  make  the  ground  appear  clear 
enough  for  recognition.  Numerous  systems  of 
lighting  aerodromes  have  been  tried,  and  new 
methods  are  being  experimented  with  con- 
tinually. The  first  method  employed  was  the 
use  of  petrol  flares,  which  are  nothing  more 
than  buckets  of  petrol  set  on  fire.  This  method 
is  still  in  use,  but  it  is  essentially  a  makeshift, 
being  both  dangerous  and  expensive. 

The  use  of  electric  lights  affords  the  greatest 
efficiency,  at  the  same  time  making  it  possible 
to  turn  all  the  lights  on  or  off  simultaneously. 
The  lights,  whether  flares  or  electric  lights,  are 


placed  so  that  when  lit  they  form  from  the 
aviator's  position  a  wide  arrow,  which  points 
into  the  wind.  The  aviator  lands  in  the  wide 
part  of  the  arrow,  and  since  the  aeroplane  pro- 
ceeds toward  the  point,  he  flies  into  the  Avind. 

In  a  recent  article  in  "London  Aeronautics," 
a  writer  gives  interesting  information  on  night 
flying,  with  special  regard  to  conditions  ob- 
taining in  England  and  in  France,  as  fol- 
lows: 

"The  conditions  of  night  flying  in  England 
and  in  France  are  vastly  different:  in  many  in- 
stances pilots  fresh  from  England  have  had  no 
previous  experience  in  it,  while  others  who  have 
flown  a  lot  are  not  up  to  the  same  flying  stand- 
ard as  those  who  are  initiated  out  there.  Any- 
way, they  all  require  a  lot  of  practice  from  a 
military  viewpoint. 

"Individual  opinions  often  differ  as  to  the 
merits  of  particular  machines,  and  it  is  not  often 
that  one  gets  such  a  unanimity  of  view  as  is  ex- 
pressed in  favor  of  a  certain  type  in  regard  to 
its  nocturnal  qualities.  It  makes  an  excellent 
night  flier  and — more  important — night  lander; 


Powerful  searchlight  for  illuminating  hangars. 


Searchlignt  illuminating  landing  ground. 


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TEXTBOOK  OF  MILITARY  AEROXAUTICS 


French   aeroplane   for   night  operations   showinjir  the  searchlight    on   the    machine    and   small    lights   under    the    bottom    wing. 

General  Pershing  is  visiting  French  aviation  camp. 


pilots  with  verj'^  little,  or  sometimes  no  experi- 
ence in  this  art  of  flying  invariably  make  good 
landings  on  these  machines.  Xatiirally,  pilots 
with  insufficient  experience  are  not  permitted  to 
take  up  observers  to  fill  the  passenger's  seat,  and 
consequently  ballast  is  required  to  give  the  ma- 
chine longitudinal  stability.  This  type,  being 
perhaps  the  most  successfully  designated  of  the 
R.  A.  F.  productions,  is  extremely  tail  heavy 
without  its  full  complement,  and  even  with  100 
lbs.,  is  still  light;  pilots  will  find  that  135  lbs. 
weight  will  give  the  best  results  and  will  eradi- 
cate any  jerky  tendency  should  the  engine  suf- 
fer from  'variable  pull' — in  fact,  the  machine 
has  been  safely  flown  'hands  off".' 

"While  on  the  subject  of  landing,  it  is  inter- 
esting to  note  that  the  French  have  an  excellent 
landing  system,  very  similar  to  our  own,  which 
has  been  extensively  used  during  the  recent  and 
present  Verdun  operations.  Barring  unfortu- 
nate contingencies,  French  machines  are  not 
permitted  to  land  until  they  get  the  signal  'AH 
clear'  from  below.  When  a  French  pilot  ar- 
rives over  what  he  thinks  is  his  own  aerodrome, 
he  circles  around,  .sending  his  own  special  letter 


in  IMorse  by  searchlight;  this  should  be  answered 
by  one  of  the  ground  projectors,  and  a  machine 
should  never  land  until  the  call  has  been  an- 
swered, the  main  idea  being  to  prevent  machines 
landing  on  hostile  aerodromes  or  even  on  those 
of  neighboring  squadrons. 

"The  method  in  use  in  British  squadrons  is 
for  a  pilot  on  approaching  an  aerodrome,  and 
wishing  to  descend,  to  fire  one  of  his  Very 
lights.  The  predetermined  signal  will  be  an- 
swered from  the  ground.  If  the  signals  agree, 
the  pilot  will  know  he  is  over  his  own  drome  and 
may  accordingly  land.  If  the  signals  do  not 
agree,  he  will  recognize  from  the  color  of  the 
ground  the  signal  of  the  aerodrome  he  is  over. 
As  every  pilot  should  memorize  the  signals  of 
adjacent  aerodromes,  this  method  will  also  as- 
sist him  in  determining  his  course  for  his  own 
aerodrome.  The  distribution  of  landing  flares 
is  on  the  foHowing  .system: 


Three  flares  in  line,  so 0 

One  flare  in  the  R.  H 1 

bottom  corner,  so 


0 

0 

2 

3 

0 

4 

NIGHT  FLYING 


129 


"A  pilot  wishing  to  descend  should  know 
by  prearrangement  which  of  these  flares  are 
doubled  so.  There  is  a  different  one  in  each 
brigade.  The  vai'ious  aerodromes  and  land- 
ing stations  in  a  brigade  are  distinguished  by 
the  color  of  the  Very  lights  fired  from  a  spot 
adjacent  to  the  double  flare.  Owing  to  mili- 
tary exigency,  it  is  impossible  to  state  more 
plainly  the  code  on  which  this  is  based. 

"Flare  lighting  is  controlled  by  the  Brigade 
Headquarters.  They  are  lighted  on  receipt  of 
orders,  and  are  kept  going  until  ordered  out. 
At  its  discretion  a  Brigade  Headquarters  may 
request  a  neighboring  aerodi'ome  to  'flai'e  up.' 
Pilots  flying  at  night  are  individually  responsi- 
ble for  informing  their  Brigade  Headquarters 
of  their  safe  atterrisage. 

"Night  flying  is  dependent  largely  upon  the 
weather,  but  for  our  purpose  can  be  divided  into 
two  categories — moonlight  nights  and  other- 
wise. When  conditions  are  good,  and  the  moon 
bright,  perfect  night  flying  can  be  practised  and 
observations  taken  easily  up  to  a  height  of  9000 
ft.;  landing  grounds  and  aerodromes  can  be 
seen  quite  plainly  at  this  height,  although  on 
ascent  the  machine  is  quickly  lost  to  view  from 
below.  So  difficult  is  it  to  spot  machines  at 
night,  unless  carrying  distinguishing  lights,  that 


Aeroplane  searchlight  mounted  on  a  biplane.  The  search- 
light, 500-watt  power,  is  operated  by  a  wind-wheel  and  has  no 
connection  with  the  aeroplane  motor.  It  is  designed  to  be  used 
as  a  signal  light  and  to  aid  in  making  landings  at  night. 


a  hostile  machine  over  the  lines  on  one  occasion 
could  neither  be  seen  from  the  ground  nor  the 
air.  On  occasions  when  our  machines  pene- 
trate over  the  lines  the  enemy  guns  cease 
firing,  presumably  so  that  gun-flashes  shall 
not  be  spotted.  Under  the  most  perfect 
conditions  railways  are  difficult  to  see,  but 
sometimes  a  train  may  be  recognized  by  its  white 
smoke. 

"With  no  moon,  at  5000  ft.,  it  is  not  possible 
to  distinguish  railways,  roads,  or  rivers;  but 
aerodrome    flares    are    quite    effective    at    this 


1 

u  i. 

— "^ni^^^^H 

jjjj^ 

i 

"l"''''^^^,     %\ 

ifKI^       ^^^I^^^^^^B 

■'■:^^^^&::00M.'^mM 

German  aeroplanes  at  a  German  aerodrome  at  night. 


130 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


A  Taube  at  dusk. 

height — in  short,  on  moonless  nights  only  lights 
can  be  seen.  Even  on  "moony"  nights,  at  2000 
ft.  unlighted  objects  cannot  be  seen  with  any 
certainty  on  the  road ;  yet  at  7000  ft.  on  an  ideal 
night,  roads  are  clearly  seen  looking  vertically 
down,  and  lighted  motor  transports  are  easily 
discernible.  Villages  and  towns  are  also  "on 
view";  the  British  trenches  may  also  be  seen 
with  the  aid  of  flares. 

"The  danger  of  keeping  aerodromes  'flared' 
while  machines  are  out  on  reconnaissance  re- 
sults sometimes  in  hostile  machines  (which  can- 
not be  placed)  dropping  bombs. 

"We  have  by  no  means  reached  finality  in  the 
design  either  of  parachute  flares  or  wing-tip 
flares.  Of  two  parachutes  tried  recently,  only 
one  burned,  while  the  other  flare,  on  exam- 
ination, was  found  to  be  only  partially  burned ; 
the  latter  flare  ignited,  burned  steadily  for  a 
short  time,  and  then  went  out,  with  half  the 


composition  unburned.  This  is  extremely 
dangerous,  as  it  leaves  the  pilot  in  the  dark  just 
at  the  moment  of  landing,  when  he  most  needs 
the  light.  The  arm  of  the  flare  is  apparently 
too  weak,  and  becomes  bent  in  the  course 
of  flying.  If  bent  so  as  to  bring  the  flare 
close  to  the  wing,  it  should  work  satisfactor- 

ily. 

"In  view  of  the  landing  difficulty,  the  sugges- 
tion that  every  aerodrome  should  be  equipped 
with  a  portable  projector  is  excellent.  Pro- 
vided the  jjilot  is  always  able  to  land  head  on  to 
wind,  the  beam  remains  pointed  to  windward. 
Great  care  must  be  taken  to  keep  the  beam  sta- 
tionary, as  any  glare  in  a  pilot's  eyes  would  blind 
him  and  have  unfortunate  results. 

"A  closing  hint  to  flight  and  squadron  com- 
manders might  not  be  out  of  place  here. 

"Pilots  detailed  for  night  flying  should  have 
plenty  of  opportunity  to  practise  on  the  same 
machines  vith  which  they  will  fly  at  night,  and 
should  be  instructed  to  practise  the  following 
operations : 


•  •>••■.••'..'.■■.-. 


.'iJ^'J'^...'.' 


'->- 


Cross-sectional  view  of  one  of  flie  new  German 
aviation  iK-acons 

Couneay  acientiflc  AmtrUxm 


NIGHT  FLYING 


131 


I 


Lighting  stand,  serving  the  double  purpose  of  guiding  nocturnal  flyers  to  a  safe  landing  and  detecting  hostile  aeroplanes. 


-I.e. 


with- 


1.  Flying  by  instruments  alone- 
out  using  the  horizon  as  a  guide, 

2.  Gliding  slowly. 

3.  Making  small  sideslips  and  quick  recov- 
eries. 

4.  Checking  the  speed  of  the  machine  and 
identifying  it  with  the  sound  of  the  wires  under 
certain  conditions. 

5.  Turning,  using  instruments  alone, 

6.  Landing  slowly." 

The  "Honig  Circles"  Signals  for  Night 
Flyers 

The  ingenious  arrangement  of  signals  for 
night  fliers,  patented  by  the  German  architect 
Edgar  Honig,  was  described  in  the  Technische 
Monatsnefte  and  translated  in  the  Literary  Di- 
gest. The  apparatus  consists  of  two  concentric 
circles  or  rings  of  incandescent  lamps  standing 
on  edge  a  few  feet  from  the  ground,  with  the 
smaller  one  placed  at  a  distance  of  several  yards 
behind  the  larger  one,  which  stands  back  of  the 
landing  stage. 

The  working  of  this  arrangement  depends  on 
the  wellknown  fact  that  a  circle  appears  as  an 
ellipse  as  soon  as  the  eye  ceases  to  be  directly 
opposite  the  center.  Hence  two  circles  of  light, 
arranged  as  Figure  1,  must  be  perceived  as  two 


upright  or  slanting  ellipses  which  either  inter- 
sect each  other  or  have  the  smaller  contained  in 
the  larger,  until  the  eye  of  the  beholder  is  directly 
in  line  with  the  axis  passing  through  the  middle 
point  of  the  two  circles.     In  the  case  of  the 


X'hotograph  of  the  IliiTiig  Circle.^. 


:^";5 


132 


TEXTBOOK  O^  MILITARY  AERONAUTICS 


i. — From  above,  the  aviator 
sees  two  ellipses  only. 


3. — As  he  descends,  the 
circles  round  out  and  cut 
each  other. 

Honig  Signal  Circles 
whose  central  axis 
stands  about  13  feet 
above  ground,  this  occurs  when  the  airman  is 
from  two  to  three  feet  (according  to  the  build 
of  the  machine)  above  the  ground. 

Figure  2  shows  how  the  circles  appear  to  a 
flier  who  finds  himself  at  a  great  height  above 
the  signal  and  flies  directly  down  in  the  direc- 
tion of  the  central  axis  of  the  circles.  When  he 
comes  farther  down,  probably  flying  in  a  spiral 
and  thus  nearing  tbe  ground,  the  rings  begin  to 
intersect,  and  appear  to  him,  for  instance,  as  in 
Figure  3.  This  position  of  the  light-circles  re- 
veals to  him  not  only  that  he  has  approached  the 
earth,  but  also  that  he  has  diverged  from  the  di- 
rection of  the  middle  axis,  and  that  he  must 
steer  his  machine  to  the  right  in  order  to  obtain 


-"Earth  level!     Steer 
left!" 


5. — ■'"Home !" 


the  right  direction  again.  He  does  this,  still 
continuing  to  descend  until  he  sees  the  signal, 
perhaps  as  in  Figure  4.  He  knows  then  that 
he  has  approached  the  level  of  the  ground. 
Consequently  he  steers,  and  the  operation  con- 
sists merely  of  turning  on  the  current  when  a 
machine  is  heard  approaching  at  night,  in  cases 
where  the  lights  are  not  needed  to  bum  con- 
tinuously. Where  the  signal  is  part  of  the 
equipment  of  an  aviation  corps  in  an  army,  it  is 
easily  arranged  so  that  the  rings  can  be  fastened 
together  and  transported  without  difficulty 
when  camp  is  changed.  The  invention  is  like- 
wise specially  valuable  for  water  landings. 

Lights  for  Night  Landing  Grounds 

Mr.  Bright  the  British  authority  in  his  report 
on  the  best  lights  for  night  landing  grounds 
says  in  this  connection:  "While  undoubtedly  the 


I. — How  the. circles  of  light  guide  the  night- 
fliers.  The  relative  positions  of  the  two  con- 
centric light-circles  reveal  to  the  aviators,  as 
the  dotted  lines  show  (and  as  the  diiigranis  of 
the  opposite  page  indicate),  their  angle  of 
approach  to  the  aviation-ground.  See  article 
on   next  page. 


NIGHT  FLYING 


133 


light  obtained  from  the  ordinary  petrol  flare  is 
better  suited  for  the  purpose  than  the  white  light 
from  a  conmion  arc  lamp,  the  same  does  not  ap- 
ply in  the  case  of  the  comparatively  new  flame 
arc  lamps  which  are  recommended  for  this  pur- 
pose. The  value  of  the  petrol  flare  was  settled 
as  far  back  as  1885  when  the  South  Foreland 
experiments  were  conducted  at  the  instance  of 
Trinity  House  (see  "Report  of  the  Committee 
on  Experiments  at  South  Foreland  relative  to 
Electricity,  Gas,  and  Oil  as  Lighthouse  Illumi- 
nants") .  The  new  flame  arc  lamps  give  a  yel- 
low red  arc  when  the  carbons  are  made  in  a 
manner  separately  communicated.  Indeed,  the 
light  produced  by  the  yellow  flame  carbon  has 
the  highest  penetrating  power  of  any  known  il- 
luminant,  and  has  great  advantages  over  all 
others  (including  petrol  flares)  in  foggy  or  hazy 
weather.  The  light  obtained  from  these  special 
flame  arc  lamps  (fitted  with  yellow  flame  car- 
bons) is  very  near  in  color  to  petrol  flares,  but 
is  considerably  more  powerful.  A  further  im- 
portant advantage  in  an  electric  lighting  system 
of  the  special  type  named  would  be  that,  unlike 
petrol  flares,  all  the  lights  can  be  simultaneously 
switched  on  and  off  at  a  moment's  notice." 

Returning  from  Night  Flights — The  Signals 

To  the  aviator  engaged  in  long-distance  night 
raids  night  flying  still  holds  difficulties  to  be  sur- 


A    convenient    French    aerial    beacon. 


Portable  aerial  beacon  of  2400  decimal  C.P. 

mounted.  There. are  a  few  difficulties  however, 
confronting  the  aviator  on  "Zep  duty"  who  does 
not  venture  far  from  his  base.  The  long  dis- 
tance raider  may  lose  his  way  in  the  darkness; 
the  aviator  on  "Zep  duty"  only  has  to  flash  the 
signals,  and  since  the  landing  stations  in  Great 
Britain  and  France  are  numerous,  the  signal  is 
usually  answered  by  one  of  the  stations  lighting 
up  so  that  the  aviator  may  land. 

Naturally,  the  signals  are  changed  daily. 
The  authorities  issue  daily  signals  and  the  me- 
chanics load  the  signal  pistols  accordingly  for 
the  aviators.  The  lights  or  flares  can  be  seen 
from  a  distance  of  from  ten  to  fifteen  miles. 
Aeroplanes  are  also  equipped  with  lights  placed 
beneath  the  bottom  wings  and  with  automobile 
lamps  so  that  in  case  of  a  forced  landing  they 
may  come  down  with  little  trouble.  These 
lights  are  turned  down  by  pressing  a  button. 

Lighting  Equipment  of  Aeroplanes 

The  lighting  equipment  of  aeroplanes  varies 
considerably.     Following  are  the  British  Gov- 


134 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


T:-,^v/■^?r?,7l!^5,r«!2P'5SS«:  -?-^-^^ 


0k 


|NO 

IcHrr 

ppw^^ww 

^^^T^^g 

IHHI^P 

'^^B 

Aeria/  i..., „„.,t 

ernment's  specifications  for  the  lighting  equip- 
ment of  certain  battleplanes  and  the  passenger's 
bay. 

Electric  lighting  equipment.  This  will  be 
fixed  in  a  suitable  manner.  Dry  batteries  of 
the  life  of  4iA  hours  to  be  provided  to  light  up 
the  dashboard.  As  the  machine  will  not  be  fly- 
ing for  a  longer  period  than  8  hours,  the  extra 
dry  battery  provided  can  be  used  in  emergency. 
When  these  dry  batteries  are  exhausted,  they 
can  be  thrown  away.  They  weigh  about  21  lbs. 
each. 

The  lighting  to  be  arranged  as  follows : 

2.  Lights  to  throw  light  on  the  instrument 

board,  and  arranged  so  as  not  to  throw  it  in  the 

pilot's  eyes. 

1.  Light  at  the  bottom  of  the  fuselage,  to 
throw  light  on  the  floor  in  case  the  pilot  wishes 
to  throw  light  there  for  any  purpose.  This  is 
also  to  be  shaded  so  that  it  will  not  throw  light 
in  his  eyes. 

1.  Light  for  the  compass,  arranged  in  the 
same  way. 

1.  Portable  torch  to  be  provided  with  each 
machine. 


Instruments  Painted  with  Luminous 
Compounds 

The  instruments  used  by  aviators  in  night 
flying  have  the  indicators  and  dials  painted  with 
luminous  compounds,  which  eliminate  the  blind- 
ing glare  of  electricity  and  the  necessity  of  using 
flash  lamps.  The  parts  so  painted  can  be  seen 
clearly  by  the  pilot  who  for  the  time  being  is  en- 
tirely wrapped  in  darkness. 

Aerial  Lighthouses 
It  is  as  essential  that  air  men  have  hghthouses 
to  guide  them  through  the  atmospheric  ocean 
as  for  navigators  at  sea.  The  aerial  beacons 
are  of  several  types,  the  most  powerful  having  a 
candle-power  of  50,000  and  being  visible  for  up- 
ward of  fifty  miles.  As  the  result  of  much  ex- 
perimenting a  general  type  of  beacon  has  been 
developed.  It  consists  of  several  belts  of 
lenses,  with  a  powerful  lamp  at  their  focus  which 
sends  out  its  rays  uniformly  in  all  directions. 
It  is  necessary,  of  course,  that  the  light  be 
clearly  visible  to  the  air  man,  whether  flying 
above  or  below  the  light.  Each  lighthouse 
must  have  a  distinctive  mark  of  its  own,  so  that 
the  air  man  will  be  in  no  danger  of  confusing 
them  and  losing  his  way.  A  series  of  light- 
flashes  are  thrown  out,  corresponding  to  the 
dots  and  dashes  of  the  JSIorse  code.  The  air 
man  soon  learns  to  read  these  signals,  or  to  ver- 
ify them  by  a  code  book,  and  can  thus  readily 
learn  his  position,  even  when  the  earth  beneath 
him  is  completely  hidden. 

■   Adventures  in  Night  Flying 

Following  is  a  letter  from  Lieut.  Red.  H. 
Mulock,  R.  N.,  the  Canadian  pilot  who  was  the 
first  to  succeed  in  chasing  a  Zep  at  night,  and 
did  so  at  a  time  when  arrangements  for  signal- 
ing between  aeroplanes  and  aerodromes  had 
not  yet  been  completed. 

"Dear 

"We  have  had  a  little  fun  around  here.     A 


signal,   indicated   bjr   dots   and   dashes,  flashed  from  aerial   lighthouses. 


NIGHT  FLYING 


185 


Showing  the  luminous  tracks  of  three  aeroplanes  landing  at  night  at  a  military  aerodrome. 


week  ago,  or  rather  Mondaj%  the  17th,  a  Zep 
blew  along  evidently  looking  for  our  aerodrome. 
We  heard  him  coming  and  presently  saw  him 
flying  in  from  the  sea.  I  asked  our  C.  O.  if  I 
could  go  after  him,  and  got  away  with  some 
bombs,  grenades,  and  a  revolver.  He  was  steer- 
ing a.bout  due  south,  so  I  laid  a  course  east  of 
south,  and  started  to  head  him  off.  It  was  in 
the  middle  of  the  night — a  little  after  1  a.  m. 
and  no  moon,  very  dark  with  clouds  around  and 
the  stars  so  dark  you  could  not  see  the  horizon. 
He  passed  over  here  about  2,000  ft.  up,  and,  by 

the  time  he  got  to I  was  up  even  with  him 

and  to  seaward.  I  then  changed  my  course 
straight  for  him.     He  had  stopped  to  drop  his 

bombs  on and  with  his  engine  shut  down, 

heard  me  coming,  and  of  course,  as  soon  as  he 


heard  me,  looked  in  my  direction  and  must  have 
seen  the  flames  from  my  exhaust. 

"Anyway  he  did  not  wait  to  throw  anj^  more 
bombs,  and  I  saw  the  most  wonderful  sight.  I 
was  about  1,500  ft.  from  him.  He  opened  fire 
with  maxims,  but  without  effect,  and  majestic- 
ally stuck  his  nose  up  and  went  up  like  a  balloon. 
He  was  then  higher  than  I,  so  I  opened  out 

again,  and  tried  to  round  him  back  again  at , 

where  we  both  turned  out  to  sea  and  steered 
about  east.  I  chased  him  up  to  8,000  ft.  and 
over  to  the  Belgian  coast,  and  we  both  changed 
courses  to  S.  E.  and  a  little  later  went  into  the 
clouds  together  over . 

"Having  lost  him  in  the  clouds,  I  climbed  to 
9,000  ft.  and  rambled  around  waiting  for  him. 
But  he  had  gone.     There  were  two  of  them; 


136 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


one  was  given  a  warm  reception  by  the  chaps 

at ,  wliile  the  other  one  and  I  had  a  picnic 

all  to  ourselves.  He  ran  away  so  fast  I  could 
not  keep  up  with  him  and  climb  at  the  same 
time.  I  waited  around  for  him,  but  no  Zep  ap- 
peared; evidently  he  stopped  his  engines  and 
listened  for  me,  and  then  went  off  in  another  di- 
rection. There  was  no  use  waiting,  so  I  started 
for  home.  I  swung  around  out  to  sea  from 
coast,  going  north  by  compass.  It  was  very 
dark,  and  I  could  not  see  the  sea  or  land  and  no 
stars  or  moon,  as  I  was  in  the  clouds.  Talk 
about  being  alone  in  the  world,  very  few  people 
know  what  it  means.  I  came  down  to  7,500  ft. 
and  turned  west  finally,  picking  up  some  search- 
lights in  the  distance.     I  thought  they  were  at 

and  headed  for  them,  and  after  some  time. 

three  big  searchlights  jumped  out  of  the  dark- 
ness below.  Instantl}'  I  knew  they  were  from 
a  cruiser  and  were  looking  for  me,  having  heard 
my  engine.  At  night  they  fire  on  any  one,  as 
they  cannot  see  our  large  red  circles.  So,  not 
being  particularly  anxious  to  see  how  near  they 
could  come,  I  started  to  dodge  the  large  beams 
and  headed  out  north  into  the  open  sea  again. 

I  worked  my  way  gradually  back  to  the 

and  later  on  saw  the lightship,  and  then  the 

coast,  which  looked  very  dim  way  down  below, 
but  it  was  home  and  once  more  I  felt  in  the 
world. 


"I  could  not  come  down  for  two  reasons. 
First,  it  was  not  light  enough  to  land  and  sec- 
ondly, I  knew  I  would  be  fired  on  if  I  w^ent 
low.  So  I  had  to  play  around  up  in  the  sky 
over  the  sea  7,500  ft.  up  waiting  for  the  sun  to 
rise.  As  soon  as  it  was  light  enough  I  came 
down  and  every  one  seemed  glad  to  see  me  back, 
as  they  had  given  me  up.  I  cannot  begin  to  tell 
you  all  about  it,  as  one  has  to  go  through  a  night 
like  that  to  realize  what  wonderful  things  we 
have.  I  enjoyed  every  minute  of  it,  and  every 
minute  Avas  different. 

"]My  engine  gave  out  once  over  the  North 
Sea  but  was  able  to  keep  her  going  slowly,  and 
finally  as  I  was  gliding  down  to  the  ocean  for 
some  unknown  reason,  it  picked  up  again.  I 
was  going  to  glide  for  one  of  the  searchlights 
and  land  in  the  water  alongside  and  be  picked 
up  by  a  torpedo  boat,  but  luck  was  with 
me.  Dodging  searchlights  over  the  North  Sea 
is  the  finest  sport  in  the  world.  Funny,  is  n't 
it,  that  we  have  to  dodge  our  own  guns 
and  lights?  They  cannot  distinguish  between 
the  Germans  and  ourselves,  and  take  no  chances, 
so  they  fire  on  any  engine  they  hear  in  the 
sky." 

Since  the  above  was  written  arrangements 
have  been  made  for  signaling  between  aero- 
planes and  the  aerodromes.     Lieut.  William  L. 


German  i>ortable  gag  beacon. 


Aerial  beacon  with  eicctric  flashliglit. 


Tlie  aerial  brnron  at  Johnnnistal,  Germany. 


NIGHT  FLYING  187 

Robinson  who,  on  September  2d,  1916,  brought  airship  fall,  he  looped  the  loop  with  joy,  then, 
down  the  first  Zeppelin  on  British  soil,  in  relat-  "showed  my  signals  to  stop  firing,  and  came 
ing  his  exploit  states  that  after  seeing  the  huge     down  to  earth." 

Memoranda: 


138 


TEXTBOOK  OF  ^IILITARY  AERONAUTICS 


Fig.    9.     Installation    by    German 
government. 


Fig.   11.     A   Zeppelin   wireless  outfit. 


Fig.   12.    A  motor  car  wireless  station. 


Fig.    18.    Airman's    helmet    with    wireless    re- 
ceiver. 

Aero  wireless  apparatus. 
The  use  of  wireless  for  communication  be- 
tween areoplanes  and  their  bases  has  gradually 
become  more  and  more  necessary  and  to-day 
the  aviators  on  all  the  fronts  are  equipped  with 
the  most  improved  instruments  available.  For 
every  type  of  aircraft  a  suitable  wireless  set 
has  been  developed. 


Fig.     10.     Large    5    K.    W. 
Zeppelin  apparatus. 


Fig.  19.     Apparatus  for  seeing  wire- 
less signals. 


Fig.    16.    Early   German   Taube   carrying   wireless    masts   on 

wings. 


I'ig.   15.     Wireless  on  1913-14  monoplane  used  in   I-'landcrs. 


138 


A   double-motored   Caudron   biplane  used  extensively   for  observation,  in  France.    It  is  equipped  with  a  Lewis  gun. 


CHAPTER  XI 

RADIO  FOR  AEROPLANES 

By  William  Dubilier 


Unless  one  has  made  personal  observations 
as  to  the  working  of  wireless  and  air  craft  in 
this  present  war,  it  is  difficult  to  appreciate  how 
the  art  of  warfare  has  been  transformed  by  these 
two  branches  of  science;  and,  in  turn,  modern 


one  day,  and  have  been  solved  the  next.  One 
incident  may  be  mentioned  where,  in  the  early 
months  of  the  war,  wireless  stations  were  used 
for  directing  the  artillery.  The  shots  from  the 
guns,  however,  were  so  constant  and  continuous 


methods  of  fighting  have  changed  the  art  of  that  they  caused  disturbances  in  the  atmosphere, 

radio     and     aeronautic     engineering.     Recent  which,  in  turn,  seemed  to  affect  the  receptor  of 

events  and  progress  of  wireless  communications  the  wireless  station,  and  so  a  continuous  noise  or 

have  established  this  branch  of  science  as  an  in-  click  was  heard,  such  as  is  produced  by  static, 

dispensable  means  of  transmitting  intelligence  Immediately  physicists  were  set  to  work  and  this 

from  one  place  to  another.  objection  removed,  and  so,  many  other  problems 

Radio  and  aeronautic  communication  may  be  in  wireless  have  come  up,  as  communication  be- 

termed  the  nervous  systems  of  the  army  and  came    necessary    under    different    conditions, 


navy.  Even  for  the  directing  of  artillery  fire 
and  communication  between  trenches,  it  has 
been  necessary  to  resort  to  electro-magnetic 
waves  from  aeroplanes.     Problems  have  arisen 


which  enlisted  almost  every  radio  and  aero 
worker  in  the  fighting  countries.  They  had  no 
time  to  try  out  new  apparatus,  except  where 
new  conditions  arose,  and  the  instruments  pre- 


139 


140 


TEXTBOOK  .OF  MILITARY  AERONAUTICS 


U.  S.  Army  biplane  used  in  Capt. 
Culver's  experiments,  siiowing  radio 
apparatus  and  aerials. 


viously  used  were  not  suitable;  so  immediately 
the  departments  were  divided  up  into  sections. 
The  practical  men  were  set  to  work  installing 
and  making  stations  as  fast  as  the  factories 
could  turn  them  out,  and  the  experimenters  and 
physicists  were  ready  to  try  out  new  apparatus 
and  rectify  new  objections. 

Wireless  and  aeroplane  companies  in  France, 
England,  and  the  other  countries,  except  Ger- 
many, were  not  so  numerous  or  as  large  as  they 
are  in  this  country,  and  so  their  output  was  soon 
limited,  which  was  much  below  the  demand. 
Everything  obtainable  was  used  for  wireless. 
The  old  type  induction  coils,  apparatus  which 
was  placed  in  the  junk  heap  10  years  ago,  all 
became  very  handy,  due  to  the  fact  that  the 


Virw   of  the  e<xk-pit,  sliowinjf   nrrnntfcnient  of  the  Culver  set 
which  transmitted  119  miles. 


Government  was  unable  to  obtain  small  sets, 
and  that  the  radio  companies  paid  so  little  atten- 
tion to  this  branch. 

For  this  reason  England  subsidized  many  of 
the  large  factories,  such  as  the  Sterling  Tele- 
phone Company,  and  devoted  practically  the 
whole  works  to  the  manufacture  of  small  radio 
outfits  of  the  aeroplane  tyjje,  under  her  own 
supervision.  In  Europe,  as  well  as  in  this  coun- 
try, development  in  that  direction  had  been  very 
badly  neglected  up  to  the  time  of  the  war.  All 
acquainted  with  the  present  conditions  on  the 
other  side  will  admit  that  wireless  and  aero- 
nautics is  one  of  the  most  important  assets,  if 
not  the  most  important,  and  it  is  the  small  radio 
outfit  and  the  rapid  machines  which  are  making 
it  so  essential.  I  hope  this  Government  and 
radio  engineers  in  this  country,  will  take  ad- 
vantage of  this  experience. 

In  all  the  small-power  and  portable  instru- 
ments used,  whether  they  were  the  old  appa- 
ratus or  the  newly  designed  ones,  the  transmis- 
sion has  been  in  musical  notes,  and  the  spai-k- 
gap  in  every  case  was  of  a  quenched  type. 
Even  in  the  30-  and  -iO-watt  instruments,  using 
a  T2-volt  storage  battery  with  an  ordinary  in- 
duction coil,  quenched  gaps  were  installed. 
The  copper  discs  were  ll/4  inches  in  diameter, 
14  i"ch  thick,  with  a  sparking  surface  of  about 
%  sq.  in.,  and  small  mica  rings  for  separators. 

At  first  the  wire  telephone  and  telegraph  were 
used  everywhere,  especially  between  trenches, 
but  very  frequently  the  wires  were  broken  by 
shrapnel  shell,  and  by  the  men  themselves  at 
iiigiit,  for  that  is  the  only  time  when  they  dare 


RADIO  FOR  AEROPLANES 


141 


leave  the  trenches,  and  there  is  little  possibility 
to  repair  the  damage.  So  wireless  has  proven 
to  be  the  only  uniform  and  trustworthy  means 
of  communication.  Especially  has  it  shown  its 
usefulness  to  the  flying  machine,  for  almost 
every  shot  fired  from  the  artillery  is  directed  by 
wireless  from  an  aeroplane,  which  is  constantly 
flj'ing  over  the  battlefield,  observing  the  shots 
and  immediately  signaling  back  if  they  landed 
too  far  or  too  near. 

Both  the  Central  Powers  and  the  Allies  have 
been  using  wireless  trench  sets.  These  must  be 
transported  and  operated  by  one  or  two  men. 
The  transmission  need  not  be  more  than  five 
miles,  but  the  aerials  must  be  very  low,  and  the 
instnmient  must  be  robust  and  adapted  for 
rough  usage.  Several  such  instruments  are 
now  being  supplied,  the  highest  and  smallest  of 
this  type  weighing  less  than  ten  lbs.  for  the 
transmitter,  under  five  lbs.  for  the  receptor,  and 
just  over  ten  lbs.  for  the  battery. 

For  aeroplane  use  great  developments  have 
taken  place  in  the  design  of  the  instruments. 


Two  types  are  mostly  being  used  by  the  Eng- 
lish and  French  Armies ;  one  having  a  power  of 
between  40  watts  and  less  and  the  other  1.50 
watts.  Recently  installations  have  been  made 
on  the  large  aeroplanes  built  for  England,  the 
details  of  which  cannot  be  made  public. 

In  supplying  wireless  apparatus  for  aero- 
planes, light  weight  and  compactness  are  the 
most  important  requirements.  The  efficiency 
of  the  instrument  is  no  longer  measured  by  the 
power  input  to  the  power  output.  It  is  the  dis- 
tance to  the  weight,  after  considering  reliability 
of  action.  To  cite  an  example:  it  is  interesting 
to  note  that  the  installation  on  almost  all  the 
aeroplanes  used  by  the  French  Government  is 
a  very  small  and  compact  instrument  in  which 
old  principles  were  revived,  the  same  as  used  in 
first  Marconi  and  Hertz  experiments.  There 
are  no  tuned  oscillating  circuits ;  simply  a  small 
induction  coil  with  an  independent  vibrator,  and 
the  spark  gap  connected  in  parallel  to  an  aerial 
and  ground  or  counter  capacity.  This  instru- 
ment is  very  largely  used  by  the  French  Gov- 


1 


m  -J^**V 


Students  learning  to  direct  artillery  fire  by  wireless. 
Photo   Bureau   of   Public   Information 


142 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


ernment  for  directing  artillery  fire,  where  it  is 
essential  that  the  installations  be  of  light  weight, 
with  a  range  of  communication  of  from  12  to 
15  km. 

An  independent  interrupter  is  used,  and  mu- 
sical notes  are  emitted  with  a  frequency  of  about 
300.  The  secondary  of  the  induction  coil  has  a 
verj^  high  inductance,  so,  when  connected  with 
the  aerial  and  ground,  it  is  in  tune  with  the  pri- 
mary vibrating  circuit.  Across  the  secondary 
are  connected  the  spark-gap  terminals,  mounted 
on  top  of  a  small  metal  case  and  on  the  outside 
of  the  instrument,  so  that  advantage  is  taken  of 
the  continuous  rush  of  air  to  cool  the  gap  which 
is  very  small.  This  gap  consists  of  a  copper 
tube  %"  in  diameter,  Me"  thick  for  one  electrode 
and  a  flat  disc  %"  in  diameter  for  the  other. 
By  connecting  the  aerial  and  counter  capacity 
directly  across  the  spark-gap,  the  necessity  of 
tuning  is  eliminated.  The  aerial  wire  system 
is  an  open  oscillator,  and  has  a  capacity  of 
.0002  mf. 

The  only  essential  change  recently  made  was 
in  tuning  the  vibrator  and  connecting  the  con- 
denser across  the  interrupter  and  the  primary  of 
the  induction  coil,  as  in  the  Dubilier  system  ex- 
plained later,  instead  of  the  condenser  across  the 
interrupter  alone,  as  was  customary  heretofore. 
Under  these  conditions  the  efficiency  of  the  in- 
strument is  considerably  increased,  and  the  rea- 
son for  this  will  be  shown.  The  battery  is  in  a 
small  case  containing  10  six-ampere  hour  cells, 
the  current  of  which  is  regulated  by  a  small  va- 
riable resistance.     An  ammeter  indicates  at  all 


times  whether  the  set  is  in  operation,  and  how 
much  power  is  being  used;  which  is  usually  40 
watts.  With  a  capacity  of  .0002,  the  aerial 
wire  system  radiates  1/9  ampere.  The  trailing 
wire,  which  is  used  as  the  aerial,  is  about  175  ft. 
long,  and  has  a  2  lb.  lead  weight  attached  to  it. 
The  engine  and  all  the  other  metallic  parts  on 
the  aeroplane  are  used  as  the  counter  capacity. 
This  instrument  is  used  mostly  for  short  dis- 
tance communications  by  the  rapid,  light  ma- 
chines which  are  constantly  circling  over  the 
trenches,  and  directing  the  artillery  shots. 
Communication  is  held  with  the  receiving  sta- 
tions situated  about  1  mile  behind  the  guns,  and 
from  there  to  the  gunners  a  regular  telephone 
line  is  used.  This  instrument  is  shown  in  Fig- 
ure 1. 

The  position  of  the  pilot  and  observer  is  very 
dangerous,  as  they  must  be  constantly  over  the 
enemies'  trenches  directing  the  shots,  if  they  are 
long  or  short,  or  too  far  to  the  right  or  left.  It 
is  surprising  to  see  how  rapidly  and  automati- 
cally the  whole  system  works.  As  soon  as  the 
shots  land,  signals  are  immediately  flashed  back, 
and  the  next  shot  follows  the  corrected  course 
indicated  by  the  radio  apparatus  from  the  aero- 
plane. These  flying  machines  must  be  very 
light  and  rapid,  due  to  the  dangerous  service 
they  render.  They  are  usually  two-seaters, 
containing  the  pilot  and  the  observer,  and  so 
one  will  appreciate  under  these  circumstances 
how  essential  a  few  pounds  would  be  in  the  wire- 
less installation.  In  constructing  the  con- 
densers for  these  installations,  the  Government 


The  transmissions  and 
aerials  on  a  French  bi- 
plane. 


RADIO  FOR  AEROPLANES 


148 


f 


AE.RI  AL 


Photograph  of  Zeppelin  showing  the  aerial  hanging  down. 


informed  us  that  we  must  eliminate  the  alumi- 
num castings  which  are  used  for  compresses  and 
heat  radiators,  and  must  cut  the  containing  box 
down  so  that  the  wall  is  not  more  than  %".  We 
thus  reduce  the  weight  about  1/4  lbs.,  which  sat- 
isfied them  very  much  more  than  the  former 
ones  constructed  from  careful  experiments. 

I  have  been  informed  by  the  commanders  that 
this  aeroplane  and  radio  work  has  been  the  most 
effective  done  in  the  war.  It  has  been  by  means 
of  this  radio  communication  that  it  was  possible 
for  the  artillery  to  break  up  the  strong  concrete 
trenches.  I  was  in  France  when  the  famous 
Champagne  district  siege  was  begun,  and  the 
returning  officers  informed  me  that  the  Gei-man 
trenches  were  constructed  as  though  they  were 
foundations  for  large  buildings,  heavy  concrete 
walls  reinforced  by  steel;  the  only  way  it  was 
possible  for  them  to  make  any  advance,  was  to 
completely  break  up  these  trenches,  and  only 
by  continuous  bombardment  was  it  possible 
to  get  the  men  to  move  and  make  any  ad- 
vance. 

The  flying  machines  never  stay  out  for  longer 
than  three  hours ;  when  they  return  the  batteries 
are  changed. 

Another  set  of  instruments  used  for  aero- 
plane work,  but  of  a  much  higher  power,  is  one 
using  the  Bethenod  resonance  alternator.  This 
outfit   is    shown   in   Figure    2,   installed   on   a 


French  aeroplane.  The  special  feature  of  this 
apparatus  is  the  large  power  coupled  with  the 
light  weight,  which  is  made  possible  by  the  use 
of  Bethenod's  High  Frequency  Generator. 
The  principle  of  this  alternator  is  well  known, 
and  no  further  details  are  necessary. 

This  instrument  is  made  in  two  different 
sizes.  One  weighing  35  kilos  complete,  about 
77  lbs.,  has  a  transmission  radius  of  110  km., 
about  60  miles.  The  larger  outfit,  which  weighs 
about  110  lbs.,  has  a  communicating  radius  of 


I   CHOUNO 


Methods  of  suspending  aerials  from  dirigibles. 


144 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Two  French  wireless  receiving  truclis' screened  from  the  eyes  of  the  enemy  aviators  h\   trees  and  branches. 


about  200  km.,  about  120  miles.  The  generator 
for  750  watts  outfit  at  25  volts  with  a  frequency 
of  1,500  cycles,  is  run  at  a  normal  speed  of  4,500 
revolutions  per  minute.  The  weight  complete 
for  the  generator  is  19  kilos,  about  42  lbs.,  and 
can  be  overloaded  up  to  1  KW.  Here  is  a  gen- 
erator with  %  KW  outfit,  which  weighs  only  42 
lbs.,  and  using  a  very  high  frequency  makes  it 
possible  to  cut  down  the  weight  and  size  of  the 
other  parts  of  the  installation.  In  the  tests 
made  with  this  instrument,  communication  was 
held  from  an  aeroplane  to  a  land-station  for  a 
distance  of  100  miles,  with  a  complete  installa- 
tion which  did  not  weigh  more  than  110  lbs., 
so  we  have  here  a  basis  upon  which  to  work;  a 
weight  of  1  lb.  for  each  mile  communication. 
The  apparatus  is  constructed  with  a  fairly  good 
co-efficient  of  security,  in  order  to  support  the 
shocks  of  vibration  it  has  to  experience.  The 
sending  outfit  includes  the  generator,  a  trans- 
former, an  oscillating  circuit,  and  an  aerial  wire 
system.     The    aerial    consists    of    a    bronzed. 


braided  wire,  having  a  high  mechanical  strength, 
and  hanging  down  and  back  of  the  aeroplane. 
The  diameter  of  this  braid  is  about  1  mm.,  and 
it  is  rolled  on  a  very  light  and  insulating  wheel, 
as  can  be  seen  from  the  figure.  The  end  is  an- 
chored by  a  3  lb.  mass  which  is  so  shaped  that 
when  the  aeroplane  is  in  action,  the  aerial  wire 
is  nearly  in  a  horizontal  position,  thus  having  a 
minimum  surface  exposure.  The  wheel  upon 
which  this  wire  is  rolled  is  fitted  on  a  circular 
contact,  with  facilities  for  quickly  rolling  and 
unrolling  the  wire  while  sending,  for  by  that 
means  the  aerial  wire-circuit  is  tuned.  In  case 
of  emergency,  an  insulated  clipping  is  provided 
by  automatically  cutting  off  the  wire.  The 
counter  capacity  consists  of  all  the  metallic 
parts  of  the  aeroplane  connected  together,  which 
include  the  engine,  the  generator,  and  other 
wires  used. 

The  apparatus,  including  the  wheel,  the  clip- 
ping, and  the  frame,  is  so  built  that  it  is  ad- 
justable to  any  type  of  flying  machine. 


Looking  inside  a  wireless  receiving  truck. 
Two  officers  are  receiving  messages  from  aero 
observers  and  transmitting  them  to  the  bat- 
tery. On<'  of  them  is  shown  making  a  record 
of  the  information  on  his  chart  of  the  sector, 
which  corresponds  with  the  chart  used  by  the 
observer. 


RADIO  FOR  AEROPLANES 


145 


The  transformer  is  of  a  close  core,  air-cooled 
type,  without  magnetic  leakage,  and  due  to  the 
very  high  frequency  (1,500  cycles),  it  is  made 
very  light  and  small  (Figure  2).  The  oscil- 
lating circuit  is  constructed  for  a  maximum 
wave-length  of  500  meters,  when  a  condenser  of 
.012  mf.  capacity  is  used.  The  inductance  con- 
sists of  a  flat  helix,  with  an  insulating  handle 
for  continuous  variation  for  changing  wave- 
lengths. An  interesting  feature  of  this  instru- 
ment is  the  spark-gap,  which  is  shown  at  A  in 
the  figure,  and  consists  of  a  tube  and  plate.  It 
is  so  constructed  that  the  system  of  ventilation, 
that  is,  the  rush  of  air  which  is  generated  by  the 
aeroplane  in  motion,  is  used  for  quenching  the 
spark.  The  tube  end  of  the  spark  has  a  funnel, 
B,  into  which  the  air  rushes.  The  primary 
power  supplied  is  30  amperes  at  25  volts,  and 
the  secondary  voltage  3,500.  A  small,  light- 
weight key  is  designed  for  manipulation,  and  by 
means  of  a  rheostat,  the  musical  note  of  the 
spark  can  be  changed  from  a  deep  sound  to  a 
whistle.  The  oscillating  circuit,  as  shown  in 
Figure  2,  contains  the  hot  wire  ammeter,  the 
condenser,  the  inductance,  and  the  spark-gap 
mounted  on  a  separate  frame.  The  sliding  con- 
tact is  shown  at  E,  and  is  so  constructed  that, 
when  revolved,  the  springs  are  expanded  and  it 
slides  easily  over  the  ribbon,  a  very  desirable 
feature  in  constructing  sliding  contacts  for  flat 
inductances.  In  the  very  beginning,  tube  con- 
densers were  supplied,  but  now  the  English, 
French,  and  American  Governments  are  speci- 
fying Dubilier  condensers  for  aeroplane  instal- 
lations.    The  condenser  is  one  of  the  most  im- 


— ^/\w — I 


Fig.  4. 

portant  parts  of  the  outfit,  for  not  only  must  it 
be  unbreakable,  but  of  small  size,  light  weight 
and  highly  efficient.  For  that  reason  I  will  de- 
vote a  little  time  to  explaining  the  construction 
of  this  condenser,  which  is  used  now  in  almost 
every  aeroplane  installation. 

In  constructing  condensers,  the  space,  weight, 
and  resistance  must  be  kept  very  low,  and 
hysterisis  loss  and  brush  discharge  must  be  prac- 
tically eliminated.  Also  the  condenser  must  be 
able  to  stand  up,  and  not  change  its  capacity 
after  usage  for  a  certain  time.  The  British 
Government  specifications  call  for  a  condenser 
that  should  be  well  built,  within  5  per  cent,  of 
the  specified  capacity,  and  that  capacity  should 
not  change  5  per  cent.,  after  strain  by  a  continu- 
ous overload,  for  one  hour.  Only  certain  ad- 
hesive insulation  is  permissible,  as  waxes  tend  to 


Partial  view  of  the  receiving  apparatus  inside 
of  one   of  the  wireless  trucks. 


146 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


The  reel  and  long  copper  tube  of  the  Culver  set  through 
which  the  trailing  aerial  is  paid  out.  This  reel  has  now  been 
replaced  by  one  carried  in  the  cock-pit. 


greatly  increase  hysterisis  loss.  As  the  capacity 
is  proportional  to  the  dielectric  constant,  this 
should  be  kept  as  high  as  possible  for  a  given 
weight  and  size.  It  should  have  a  very  high 
specific  resistance,  and  a  low  internal  resistance, 
and  be  able  to  withstand  twice  the  voltage.  As 
the  hysterisis  loss  in  the  condenser  increases  as 
the  square  of  the  voltage,  it  becomes  a  serious 
problem  when  capacities  for  high  voltages  and 
high  frequencies  are  desired.  The  resistance 
must  be  kept  as  low  as  possible,  and  if  the  con- 
denser is  to  be  enclosed,  which  it  is,  all  losses 
must  be  kept  low,  in  order  to  prevent  serious 
heating.  Furthermore,  means  must  be  pro- 
vided for  radiating  the  little  heat  which  is  gen- 
erated, and  so  the  condenser  is  constructed  to 
be  able  to  stand  a  certain  rise  in  temperature 
without  harmful  results.  Under  these  condi- 
tions only  homogeneous  dielectrics  can  be  used. 
No  air  or  water  must  be  allowed  to  find  its  way 
near  the  dielectric  substance,  since  only  a  small 
trace  is  liable  to  reduce  the  strength  and  effi- 
ciency. 


The  set  most  used  by  the  Allies  on  aeroplanes, 
and  which  is  probably  the  most  interesting  of 
the  portable  installations,  is  one  designed  and 
built  by  a  Mr.  Rouzet.  It  is  shown  in  Fig- 
ure 3.  These  sets  are  made  for  various  powers, 
but  the  one  most  supplied  has  a  capacity  of  150 
watts,  the  energy  being  obtained  from  an  alter- 
nator driven  by  the  aeroplane  engine.  While 
various  installations  for  this  capacity  are  being, 
made  by  the  Governments,  this  set  deserves 
much  consideration,  especially  on  account  of  the 
remarkably  low  weight.  The  complete  trans- 
mitter, including  the  self -exciting  generator  for 
150  watts,  weighs  only  17  kilos,  about  37^/1'  lbs., 
which  is  less  than  11-  of  the  weight  of  the  smallest 
set  made  in  this  country  up  to  1916.  This  in- 
stallation utilizes  a  250-cycle  self-exciting  al- 
ternator, driven  by  a  belt,  and  is  of  a  remark- 
ably light  construction,  having  an  armature 
with  two  commutators,  one  being  for  D.  C, 
used  for  exciting.  On  the  shaft  of  the  arma- 
ture is  mounted  a  synchronized  spark-gap,  from 
which  a  group  frequency  of  500  is  obtained. 
The  key  is  connected  in  the  field  of  the  gener- 
ator. The  transformer  is  close-cored,  oil- 
cooled,  and  is  enclosed  in  a  fiber  tube  as  shown 
in  Fig.  00.  The  condenser  and  the  tuning  coil 
are  very  light  but  rigid. 

In  testing  the  instrument,  I  found  at  the  end 
of  10  minutes  the  frame  became  overheated. 
However,  the  cooling  effect  obtained  by  the 
aeroplane  traveling  through  the  air  at  the  rate 
of  60  miles  an  hour  is  taken  advantage  of,  and 
under  these  circumstances  the  apparatus  works 
very  well.  In  my  opinion  the  army  and  navy 
should  utilize  such  an  instrument  for  aeroplane 
work. 

By  means  of  a  standard  aeroplane  aerial,  I 
have  seen  this  outfit  radiating  1/4  amperes,, 
communicating  a  distance  of  50  miles.  Tiiis 
transmitter  was  designed  with  the  aim  of  real- 
izing a  commercial  system  in  which  there  will  be 
no  special  or  peculiar  factors.  A  simple  alter- 
nator is  used,  which  easily  permits  the  produc- 
tion of  a  high-tension  current  necessary  to 
charge  the  condenser,  which,  in  turn,  produces 
high  frequency  oscillations  by  means  of  a  syn- 
chronized gap,  a  condenser,  and  inductance. 
The  resonance  of  the  different  factors  is  very 


RADIO  FOR  AEROPLANES 


147 


essential,  and  the  following  points  were  consid- 
ered in  originally  designing  the  apparatus. 

First,  the  condenser  is  charged  in  the  most 
favorable  manner. 

Second,  the  condenser  is  discharged  through 
a  suitable  circuit  at  the  most  favorable  moment, 
and. 

Third,  the  injurious  results  which  accompany 
the  discharge  of  a  condenser,  and  the  operation 
of  such  an  instrument,  were  reduced  to  a  mini- 
mum. 

This  was  accomplished  by  the  use  of  a  syn- 
chronized spark-gap  which  is  attached  to  one 
end  of  the  shaft  of  the  generator.  This  gap  is 
made  minutely  adjustable,  in  order  that  the  dis- 
charge may  take  place  at  the  most  favorable 
moment,  the  reasons  and  characteristics  of 
which  are  well  known.  In  the  design  and  con- 
struction of  this  gap,  the  resistance  is  reduced 
to  a  minimum  at  the  instant  of  the  discharge. 
Then  an  air  blast  is  thrown  at  the  gap  after  the 
first  few  waves  have  passed.  The  dui'ation  of 
the  discharge  is  reduced  to  a  minimum  by  point- 
ing the  spark  electrodes. 

All  the  factors  in  the  instrument  are  care- 
fully tuned,  such  as  synchronizing  the  spark- 
gap,  which  permits  of  the  proper  time  of  dis- 
charge and  also  the  time  of  charge,  correspond- 
ing to  the  variations  of  the  alternating  feeding 
current.  This,  of  course,  is  the  most  important 
feature  of  the  instrument.  The  time  of  dis- 
charges are  regulated  not  only  by  speed,  but 
also  by  placing  several  gaps  in  series  on  the 
same  wheel. 

The  generator  is  driven  at  a  speed  of  about 
4,500.     In  the  construction  of  the  apparatus 


A  French  wireless  set  about  to  be  mounted  on   an  aeroplane. 


The  set  being  mounted  on  the  aeroplane. 


The  set  mounted  on  the  Maurice  Farman  biplane. 


The  observer  operating  the  wireless. 


One   of   the   French   machines   used    for   wireless    signaling. 


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Powerful    wireless    apparatus    installed    on    Breguet    aeroplane. 

aluminum  is  used  wherever  possible,  even  for 
the  aerial,  the  length  of  which  is  usually  about 
60  meters.  The  installations  are  supplied  for 
aeroplanes  with  capacities  up  to  1  KW,  and 
consist  of  the  following  parts : 

The  generator,  with  synchronized  gap  at  the 
end  of  the  shaft,  a  transformer,  a  condenser, 
variable  inductances,  accessories,  such  as  con- 
nectors, hot  wire  ammeters,  antennae  parts,  in- 
cluding the  guide. 

The  total  height  of  a  400-watt  set  is  12y2 
inches,  length  175^  inches,  the  width,  including 
shaft,  16  inches.  It  has  a  remarkably  low 
weight  of  55  lbs.,  and  including  the  accessories, 
70  lbs. 

A  smaller  installation,  having  a  capacity  of 
80  watts  with  a  height  of  9  inches,  a  length  of 
12  inches,  and  width  of  10  inches,  and  a  total 
weight,  with  accessories,  of  33  lbs.,  is  able  to 
communicate  a  distance  of  15  to  20  miles. 

The  1  KW  installation  has  a  height  of  21 
inches,  length,  including  shaft,  18!^  inches,  and 
width  15  inches.  The  weight  of  this  set,  com- 
plete with  accessories,  is  182  lbs.,  remarkably 
low  for  such  a  big  capacity.  The  length  of 
waves  can  be  varied  up  to  600  meters.  The  dis- 
tance of  communication  for  such  an  instrument 


is  about  200  miles  from  dirigibles,  and  over  100 
miles  from  aeroplanes. 

One  will  note  the  remarkable  characteristics 
of  such  a  high-powered  instrument,  especially 
the  low  weight  and  volume.  Taking  these  fac- 
tors into  consideration,  radio  engineers  will  see 
that  this  instrument  in  efficiency,  as  compared 
to  weight  and  distance,  is  far  greater  than  any- 
thing yet  installed.  In  general,  the  question  of 
efficiency  for  aeroplane  installations  resolves  it- 
self down  to  two  points, — weight  and  distance. 

What  does  it  matter  how  mudh  power  is  used 
or  what  does  it  matter  what  wave  length  is  gen- 
erated, so  long  as  efficient  transmission  can  be 
had  over  the  greatest  distance  for  a  given 
weight?  That  instrument  is  the  best.  If  one 
could  build  a  1  KW  set  which  only  weighed  25 
lbs.,  but  which  did  not  communicate  for  a 
greater  distance  than  the  low-powered  sets, 
there  would  be  no  gain  or  no  advantage  in  mak- 
ing a  high-powered  set  of  light  weight.  So 
long  as  the  two  factors,  distance  for  given 
weight,  are  very  efficient,  the  instrument  is  effi- 
cient; and  we  hope  in  the  future  the  lessons 
taught  will  be  considered  by  designers  of  radio 
instruments. 

In  the  early  days  of  the  war,  when  it  was 
found  that  aeroplanes  had  become  such  an  im- 
portant factor  for  defensive  and  offensive  pur- 
poses, the  commanders  and  the  aeroplanes  called 
for  a  reliable  instnament  which  will  transmit  in- 
telligently, but  which  will  have  a  very  light 
weight.  The  outcome  of  this  was  the  instru- 
ment above  mentioned. 

The  current  generated  by  the  alternator, 
which  is  self -exciting,  is  fed  to  a  close-core  trans- 
former at  120  volts,  the  secondary  of  which 
charges  the  condenser  at  about  12,500  volts. 
Troubles  usually  present  in  stationarj^  spark- 
gajjs  are  eliminated.  Air  currents  caused  by 
the  rotation  and  the  movement  of  the  aeroplane 
greatly  assist  the  detonization  of  the  spark-gap 
and  cool  the  electrodes;  hence  it  is  possible  to 
use  a  large  current  without  danger  of  arcs  form- 
ing. In  this  particular  ai)paratus  the  gap- 
length  is  less  than  the  length  which  the  potential 
used  can  jump  across.  Since  this  gap  is  revolv- 
ing at  a  very  high  speed,  a  short-circuiting  effect 
takes  place,  for,  when  the  projections  of  the  re- 


RADIO  FOR  AEROPLANES 


149 


volving  electrode  approach  the  stationary  elec- 
trodes, the  discharge  takes  place,  and  the  dis- 
tance becomes  shorter,  the  gap  resistance  and 
the  energy  consumption  being  reduced  to  very 
low  values.  This  instrument,  therefore,  com- 
bines the  two  advantages  of  comparatively  high 
initial  voltage  with  a  relatively  short  average 
gap-length;  when  the  oscillations  of  the  dis- 
charge have  become  very  low  in  amplitude,  the 
gap-length  is  very  short.  The  value  of  the  in- 
ductance is  veiy  important  in  the  operation  of 
this  gap,  for  it  is  necessary  to  carefully  regulate 
the  retardation  of  the  discharge. 

The  possibilities  of  radio  engineering  would 
be  greatly  extended  if  a  small,  simple  wireless 
outfit  were  marketed,  which  could  be  used  for 
short  distances  up  to  100  miles  and  utilizing  di- 
rect current,  which  is  available  on  almost  every 
ship,  and  which  is  much  easier  to  generate. 

With  this  object  in  mind,  the  following  appa- 
ratus was  designed.  The  idea  occurred  to  me, 
in  experimenting  with  condensers  across  the  in- 
terrupter of  the  ordinary  induction  coil,  that  if 
the  oscillations  set  up  in  this  condenser  were 


passed  through  an  inductance,  and  the  time 
period  made  the  same  as  the  vibrator,  the  effi- 
ciency of  the  ordinary  induction  coil  would  be 
greatly  increased,  for,  although  this  instrument 
has  been  in  use  for  a  good  many  years,  it  is  well 
known  that  the  ordinary  induction  coil  is  very 
inefficient.  It  was  to  utilize  the  current  wasted 
in  the  condenser  that  I  conducted  a  series  of  ex- 
periments in  1909,  which  led  up  to  the  following 
system. 

I  found  that  by  means  of  tuning  the  oscillat- 
ing circuit  across  an  interrupter,  or  any  kind  of 
a  condenser-charging  device,  that  sparking  and 
arcing  are  almost  entirely  eliminated,  and  that 
musical  notes  can  be  obtained,  especially  on  the 
smaller  type  instrument,  up  to  a  very  high  pitch. 
Due  to  this  tuning  of  the  oscillating  circuit,  the 
efficiency,  considering  the  power  input  to  the 
power  of  the  aerial,  is  greatly  increased,  for  in 
the  very  beginning  we  eliminate  the  great  loss 
which  is  common  with  a  small  motor-generator 
set  for  producing  musical  notes.  In  order  to 
obtain  the  properties  and  characteristics  of  the 
musical  note  from  direct  current  by  an  ideal  im- 


An  aeroplane  being  used  for  artilkry  lire.     The  aciuplanc  tiicle,  u,er  tiie  iuiag  batteries  and  the  obsci 

the   shots    and    directs   the   man  behind    the    guns    by    wireless. 


liic  effect  of 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


Lightweight      wireless     vibrator 
aeroplanes. 


for 


Compact    form 
unit. 


pulse  excitation,  the  connec- 
tions are  made  as  shown  in 
Figure  4.  G  is  the  direct-  pj  y 
current  source  which  passes 
through  an  inductance,  A, 
an  oscillator  or  condenser  charging  device,  B, 
another  inductance,  L,  which  acts  as  the  pri- 
mar)'^  of  the  transformer,  and  a  condenser,  C. 
In  the  small-tj'pe  apparatus  the  inductance.  A, 
acts  as  an  electro  magnet  for  operating  the  oscil- 
lator, B.  We  now  have  an  oscillating  circuit, 
BCL.  C  is  made  variable  so  that  it  can  be 
tuned  to  a  desired  frequency,  which,  supposing, 
for  example,  is  500  per  second.  The  condenser 
charging  device,  B,  has  a  working  frequenc}^  of 
its  own,  and  the  two  elements,  that  is,  the  oscil- 
lator and  the  oscillating  circuit,  are  brought  into 
resonance.  Then,  and  only  then,  a  steady  and 
even  current  is  produced  in  the  secondary  of  the 
transformer,  which  charges  a  high-tension  con- 
denser. On  types  of  apparatus  using  up  to  500 
watts,  a  magnetic  mechanical  oscillator  can  be 
used,  and  in  this  case  the  electrical  frequency  of 
the  oscillating  circuit,  BLC,  will  control  to  a 
certain  extent  the  mechanical  frequency  of  the 
oscillator.  That  is  to  say,  it  will  force  the  oscil- 
lator to  charge  and  discharge  a  condenser  at  a 
desired  frequency,  so  as  to  keep  in  step  with  the 
current.  The  reasons  for  this  will  be  explained 
later. 

Mechanical  interrupters  and  condenser- 
charging  devices  can  be  considered  as  variable 
resistances.  In  the  operation  of  an  ordinary  in- 
duction coil,  care  mus-t  be  taken  to  obtain  in  the 
interrupter  the  greatest  possible  variation  of 
potential.  This  is  generally  prevented  by  the 
currents  at  the  so-called  opening  spark.  Heat- 
ing troubles  are  experienced  at  the  contacts  and 


Fig. 


Wireless  aero  transmitter. 


of    wireless 


50   volts.     This 
the    contact    is 


arcing  occurs.  When  the 
contacts  of  an  induction  coil 
are  opened,  a  small  arc  is 
formed,  and  if  the  current  is 
over  2  amperes,  we  have  a 
potential  difference  of  about 
remains  continuous,  even  if 
opened  by  a  millimeter  or 
two.  With  weaker  currents  the  arc  potential 
is  higher,  so  that  with  the  small  working  po- 
tentials onlj^  small  opening  sparks  occur.  To 
remove  this  arc  and  to  obtain  higher  poten- 
tials at  the  interrupter,  condensers  are  con- 
nected in  parallel.  When  the  contacts  are 
opened,  the  arc  rarely  exists  below  50  volts,  but 
in  the  meantime,  however,  the  point  of  contacts 
have  already  been  extended,  and  the  potential 
difference  rose  to  several  hundred  volts.  If, 
however,  inductance  is  added,  we  will  have  cur- 
rents stored  up  in  the  condenser  which  will  dis- 
charge in  a  certain  time,  depending  upon  the 
values  of  the  inductances  and  the  capacity. 

I  therefore  tried  to  obtain  a  condenser-charg- 
ing interrujiter  which  would  operate  when  prac- 
tically no  current  was  passing,  to  prevent  any 
potential  difference  occurring  immediately  after 
the  interrupter  was  opened  and  closed;  either 
case  of  which  would  cause  the  current  to  jump 
across  the  small  air-gap.  This  condition  can  be 
fulfilled  bv  means  of  the  resonance  oscillator  and 


RADIO  FOR  AEROPLANES 


151 


circuit.  Figure  5  shows  a  curve  of  the  different 
currents,  and  the  action  taking  place  in  the  oper- 
ation of  the  apparatus. 

OY  represents  the  currents  and  OX  the  time. 
For  the  purpose  of  illustration,  suppose  the 
origin  to  commence  on  the  moment  when  the 
condenser  of  the  tuned  oscillating  circuit  is  fully 
charged,  and  the  oscillator  is  closed.  If  this 
oscillating  circuit  were  kept  closed  permanently, 
the  condenser  would  discharge  through  the  oscil- 
lator, and  the  primary  of  the  transformer  as  a 
damped  wave,  indicated  by  the  curve  OABCD. 
At  the  same  time  the  primary  current  gradually 
rises  from  zero,  according  to  the  ordinary  ex- 
ponential law,  as  shown  by  the  curve  OVEFG. 
In  this  type  of  apparatus  the  inductance,  A,  acts 
upon  the  oscillator,  so  that  OY'  represents  the 
current  through  the  magnets  necessary  to  pro- 
duce a  force  equal  to  the  controlling  force  of  the 
spring. 

In  all  types  using  an  electro-magnetic-con- 
trolled oscillator,  A  is  the  magnet  coil  operating 
on  a  spring  which  controls  the  oscillator,  D. 
Let  O  Y'  represent  the  current  through  the  mag- 
nets necessary  to  produce  a  force  equal  to  the 
controlling  force  of  the  spring.  This  is  also 
shown  at  E.  The  magnetic  force  of  the  coil,  A, 
however,  must  be  a  little  more  than  the  force  of 
the  spring,  in  order  to  control  it.  This  is  shown 
at  F.  When  the  primary  current  through  the 
magnet  coil.  A,  reaches  this  point,  F,  the  oscil- 
lator is  opened. 

For  there  to  be  no  sparking  or  arcing  at  the 
oscillator,  there  must  be  no  current  flowing  when 
it  opens.     Adding,  therefore,  the  two  cui-rents, 


An    improvised    receiving    station    constructed    with    aeroplane 
packing  boxes. 

going  through  the  oscillator  and  the  primary  of 
the  transformer,  represented  by  the  curves 
OABCD  and  OVEFG,  we  get  OHKEN,  the 
curve  of  the  total  current.  This  curve,  it  is 
seen,  falls  at  zero  when  the  ordinate  NC  is  equal 
to  the  ordinate  NF.  It  is  therefore  evident 
that,  by  varying  the  capacity  E  and  the  resist- 
ance or  inductance  of  the  primary  current  sup- 
ply, which  determine  the  curves  OVEFG  and 
OABCD  respectively,  it  becomes  possible  to  so 
adjust  the  factors  that  OHKN  reaches  zero  at 
the  instance  of  rupture  of  the  circuit,  and  under 
these  conditions  there  will  be  no  sparking  at  the 
oscillator. 

The  primaiy  current  through  the  coil  A  does 
not  cease  instantly,  but  slowly  dies  away  as  the 
condenser,  C,  charges,  such  as  is  shown  by  curve 
FP.  This  is  the  charging  current  for  the  con- 
denser. We  complete  the  corresponding  curve, 
CQR. 

This  charging  current  flows  through  the  coil 
A  and  serves  to  retain  the  oscillator,  thus  keep- 


A  "T.  S.  F."  (telegraphic  sans  fils)  post  which 
receives  the  messages  from  the  aero  observers 
and  transmits  them  to  the  gunners  on  the  French 
front. 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


Permanent  German  wireless  stations,  used  by  Zeppelins  be- 
fore the  war.  It  is  understood  that  the  number  of  these  sta- 
tions has  been  increased  greatly  since  the  war. 

ing  the  oscillator  open  until  some  such  point  as 
S  is  reached,  the  ordinates  OS  being  slightly  less 
than  OY.  Here  the  oscillator  closes  again  and 
the  operation  is  repeated,  commencing  from  the 
point  D. 

From  the  above  it  is  obvious  that  the  induc- 
tance, A,  resistance,  R,  and  capacity,  C,  play  im- 
portant parts  for  the  smooth  operation  of  this 
instrument,  and  this  is  very  well  proven  by  ex- 
periment. Further  in  order  for  the  note  to  be 
a  pure  one,  it  is  necessary  that  the  second  cycle 
must  commence  precisely  at  the  point  D,  and 
this  can  be  secured  by  varying  resistance  R  and 
the  tension  of  the  oscillator  reed. 

Furthermore,  it  is  at  once  seen  that  if  the  ca- 


Wirelru  receiving  apparatus. 


pacity,  C,  is  increased,  the  curve  FSP  Avill  de- 
crease less  rapidly,  and  consequently  the  effec- 
tive duration  of  the  current  through  C,  repre- 
sented by  distance  ND,  will  be  increased,  and 
therefore  the  contact  will  remain  open  for  a 
longer  period,  closing  at  some  such  point  as  T. 
But  the  curve  OABCD  will  also  have  a  greater 
time  period,  and  will  therefore  approach  zero  at 
some  point  near  T,  so  that  the  effective  fre- 
quency of  the  oscillator  is  lowered.  Resonance 
is  then  obtained  by  re-adjusting  the  primary  re- 
sistance R,  or  spring,  on  the  oscillator. 

If  the  voltage  is  lowered,  the  new  curve  of  rise 
of  the  current  will  not  reach  so  high  an  ampli- 
tude; hence  the  time  it  is  above  the  line  Y  EZ 
would  be  shortened  and  the  frequency  increased, 
but  resonance  is  again  obtained  by  increasing 
the  capacity. 

The  same  result  can  be  obtained  by  revolving 
commutators,  but  in  this  case  the  time  of  contact 
and  the  time  that  the  circuit  is  open  must  be 
regulated  with  the  primary  curve  and  the  con- 
denser capacity.  Then  practically  the  same  re- 
sults and  curves  can  be  applied. 

Going  back  to  Figure  4,  by  substituting  an 
oscillator  at  B,  which  has  a  continuous  varying 
resistance,  such  as  a  microphone-carbon  cup,  it 
can  be  seen  at  once  that  sine  waves  could  be 
generated  at  S,  whose  frequency  will  be  equal 
to  the  frequency  of  the  oscillating  circuit  CLB. 
The  frequency,  however,  is  limited  by  mechani- 
cal action,  but  for  laboratory  use,  I  have  con- 
structed a  small  oscillator  whose  movements  are 
very  small,  but  sufficient  to  produce  alternating 
frequencies  almost  beyond  audibility.  In  using 
revolving  commutators,  the  amount  of  fre- 
quency that  can  be  obtained  depends  upon  the 
speed  and  the  size  of  the  contacts,  so  that  in 
order  to  obtain  radio  frequencies  with  such  an 
apparatus,  almost  cannon-ball  speed  would  be 
necessary,  which  is  mechanically  impracticable, 
although  the  contacts  can  be  very  small  for  large 
powers,  and  may  be  divided  into  any  number, 
making  and  breaking  at  the  same  time.  If  it 
weie  possible  to  make  and  break  the  circuit,  at 
a  radio  fre(iuency,  under  this  system  an  ideal 
wireless  outfit  could  be  produced,  with  efficien- 
cies unknown  heretofore. 

Figure  6  illustrates  a  little  instrument  used  on 


RADIO  FOR  AEROPLANES 


158 


During  the  Balkan  War  aeroplanes  were  first  used  to  spot  artillery  fire. 


?-^4^^'-V  ;^t 


aeroplanes  with  direct-current  storage-batteries, 
30  volts. 

An  Allied  Government  has  ordered  a  num- 
ber of  these  sets  for  aeroplane  work  which 
utilize  a  small  direct-cur- 
rent generator.  This  is 
the  simplest  form  of  gen- 
erator suitable  for  aero- 
plane use,  as  it  takes  up 
smaller  space  and  is  of 
lighter  weight  for  a  given 
power  than  any  other 
sources  supplied.  The 
instrument  used  is  shown 
in  Figure  7  and  operates 
on  the  Dubilier  principle 
of  producing  musical  al- 
ternating currents  from  t 
direct,  without  the  use  of 
a  motor  generator  set. 
The  complete  weight  of 
the  apparatus  is  32  lbs. 
for  150  watts,  which  is 
sufficient  to  communicate 


a  distance  of  over  50  miles.  In  Figure  7,  the 
operation  of  this  instrument  is  the  same  as 
shown  in  the  diagrams.  The  quenched  spark 
gap.  A,  is  one  especially  designed  for  aeroplane 


The  Cutting  A  Washington  aerophone  radio  set. 


154 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


instruments,  for  it  combines  a  large  sparkling 
and  cooling  surface  with  light  weight  and  small 
space,  and  consists  of  a  long,  flat,  copper,  cast- 
ing-bar separated  about  .005",  between  which 
the  sparking  takes  place.  A  is  a  hot-wire  meter 
which  will  indicate  at  all  times  the  amount  of 
current  which  is  being  radiated,  and  D  is  the 
primary  current  which  shows  how  much  power 
is  being  consumed. 

Experiments  were  tried  both  in  France  and 
in  this  country  in  using  an  aerofan  to  drive  the 
generator  for  the  source  of  supply  to  operate 
the  wireless  instrument. 

A  patent  recently  issued  to  F.  W.  Cotterman 
comprises  a  generator  for  use  in  aeroplane  work, 
wherein  constant  potential  is  obtained  irrespec- 
tive of  the  speed  of  the  generator  by  means  of 
gears. 

Figures  9  and  10  show  installations  used  by 
the  German  Government. 

Figure  11  shows  the  method  of  suspension 
from  the  Zeppehn.  Great  care  must  be  taken 
here  that  sparks  and  induce  currents  do  not  ig- 
nite, because  at  first  it  was  thought  utterly  im- 
possible to  install  wireless  apparatus  on  balloons, 
on  account  of  this  danger.  Figure  11  shows  the 
method  of  suspension  wherein  the  instrument  is 
entirely  isolated  from  the  bags. 

In  connection  with  aeroplane  work  it  is  nec- 
essary that  automobile  stations  be  equipped  so 
that  they  can  communicate  with  these  aeroplanes 


The   fan-<lriveii   ({'■'""''''toN  '<"■  """  Culver  sot,  which   fiiriiishc-<i 
power  to  lend  message*  over  a  distance  of  140  miles. 


from  the  field,  and  if  necessary  be  quickly  mov- 
able. Figure  12  shows  an  interior  of  an  auto- 
mobile equipped  with  a  2  KW  transmitter, 
which  can  communicate  up  to  a  distance  of  150 
miles  or  so. 

Germany  has  long  foreseen  the  possibilities  of 
wireless  communication  in  connection  with  aero- 
nautics and  for  that  purpose  has  established  a 
chain  of  stations  around  Germany  which  are  in 
constant  touch  with  aeroplanes  and  balloons,  the 
same  plan  we  are  now  trying  to  carry  out  in  this 
country.  It  may  be  interesting  to  note  that  this 
is  veiy  old  and  has  been  utilized  in  Germany 
years  ago.  Figure  14  shows  the  location  of  all 
the  wireless  stations  around  Germany,  espe- 
cially used  for  aeroplane  and  Zeppelin  com- 
munications. 

iVIany  experiments  have  been  made  to  find  out 
the  best  possible  method  of  mounting  aerials  for 
radiating  along  surfaces.  The  most  convenient 
and  general  all-around  efficient  means  is  to  drop 
a  trailer,  and  to  use  the  rest  of  the  metal  parts 
of  the  aeroplane  as  the  counter  capacity.  Fig- 
ure 15  shows  a  wireless  aerial  on  a  Flanders 
aeroplane,  and  it  may  be  interesting  to  note  that 
this  picture  was  taken  two  hours  before  both  the 
pilot  and  the  operator  were  killed  by  the  same 
machine  falling. 

Figure  16  shows  a  German  Taube.  Here 
can  be  seen  plainly  how  the  aerial  is  mounted 
on  two  small  masts  on  the  extreme  of  the  wings. 

Figure  17  shows  other  methods  of  suspending 
aerials,  and  methods  of  transmitting  electro- 
magnetic waves  from  air-vessels. 

For  aeroplanes  it  is  practically  impossible  to 
receive  signals,  and  never  necessary.  It  is  only 
important  to  send,  and  very  rarely  does  an  occa- 
sion occur  where  the  operator  or  pilot  has  need 
or  time  to  receive  messages.  However,  many 
attempts  were  made  to  produce  instruments 
which  would  make  it  practical  to  receive  on  aero- 
planes, but  up-to-date  no  such  instrument  has 
yet  been  perfected.  On  account  of  the  noise 
due  to  the  engine  and  the  wind,  it  naturally  be- 
comes very  difficult  to  distinguish  signals  by 
means  of  the  ear.  Figure  18  shows  an  airman's 
helmet,  where  the  receivers  were  constructed 
right  inside  the  head-gear,  with  cushions  all 
around  to  eliminate  the  noises,  but  then  the  vi- 


RADIO  FOR  AEROPLANES 


155 


brations  of  the  body  and  slight  unavoidable 
noises  transmitted  directly  through  the  body 
make  it  impracticable  to  receive  in  this  manner. 
However,  it  is  not  impossible  to  make  an  instru- 
ment wherein  the  received  signals  can  be  distin- 
guished by  means  of  variation  in  light,  for  vibra- 
tion and  noises  will  not  interfere  with  one's 
sight.  Experiments  have  been  conducted  along 
these  lines,  receiving  the  wireless  signals  by  an 
illuminating  method,  and  Figure  19  shows  an 
instrument  constructed  on  the  principle  of  an 
eithoven  galvanometer,  wherein  the  operator 
looks  into  the  two  eye-pieces  and  can  see  the 
movement  of  lights,  indicating  dots  and  dashes. 
This  instrument,  however,  is  not  perfected  as 
yet  so  as  to  be  called  practicable. 

Due  to  encouragement  given  radio  engineers 
by  the  radio  division  of  the  United  States  Navy, 
an  apparatus  has  recently  been  developed  in  this 
country  which  is  far  superior  to  any  used  in 
Europe.     Of  the  different  installations  recently 


purchased  by  the  Navy,  three  different  princi- 
ples were  utilized  for  the  protection  of  electric 
oscillations. 

The  apparatus  supplied  by  the  Marconi  Co. 
and  E.  J.  Simon  of  New  York,  uses  a  500- 
cycle  generator,  the  former  with  1  KW  capac- 
ity, sufficient  to  communicate  about  300  miles, 
weighing  complete,  with  generator,  100  lbs., 
while  the  latter  with  about  750  watt  capacity, 
250  miles  distance,  weighs  complete  100  lbs. 

Apparatus,  using  a  glass  bulb-generator,  has 
been  supplied  and  built  by  the  De  Forest  Tele- 
graph and  Telephone  Co.  and  Western  Electric 
Co. 

Apparatus  using  direct  current,  designed  and 
patented  by  William  Dubilier,  is  being  supplied 
by  the  Sperry  Gyroscope  Company.  It  utilizes 
the  quenched-arc  principle  and  a  complete  in- 
stallation, weighing  about  65  lbs.,  with  the  gen- 
erator of  500  watt  capacity  can  radiate  over  6 
amps.,  and  communicate  about  250  miles. 


A  Zeppelin  over  Berlin.     In  the  foreground  is  the  Hindenberg  statue. 


An  American  "Blimp"  and  obscrvaliein  balloon  nt  the  Goo<lyear  School,  Akron,  Ohla 

Passed  by  the  Censor. 
ISO 


CHAPTER  XII 
MILITARY  AEROSTATICS 


Military  aerostatics  comprise  three  branches, 
as  follows: 

(1)  Dirigibles,  which  are  used  extensively 
for  night  scouting,  bombing,  and,  to  some  ex- 
tent, for  transportation  of  military  personnel 
and  material  to  otherwise  inaccessible  places; 

(2)  Captive  Observation  Balloons,  which 
are  used  for  directing  artillery  fire,  and  for  gen- 
eral observation; 

(3)  Spherical  Balloons,  which  are  now  used 


scription  of  the  latest  Super  Zeppelins,  see 
chapter  on  Naval  Airships,  "Textbook  of  Naval 
Aeronautics,"  Century  Co.  publishers. 

(2)  The  semi-rigid  dirigible  has  a  rigid 
longitudinal  frame  usually  immediately  below 
the  gas  bag;  this  frame  serves  to  distribute 
evenly  the  ascensional  strains  against  the  sup- 
ported weights  of  engine,  passengers,  etc.,  to 
prevent  buckling  of  the  gas  bag  which  in  most 
dirigibles  of  this  class  depends  upon  internal  gas 


only  for  training  captive  balloon  and  dirigible     pressure  to  maintain  the  shape  of  the  envelope. 


pilots. 


Dirigible  Balloons 


Hundreds  of  dirigible  balloons,  ranging  in 
size  from  the  small  "Blimp,"  about  180  feet 
long,  to  the  huge  700  foot  "Zeppelin,"  are  used 
in  the  present  war.  The  "Blimps"  are  used 
mainly  for  coast  patrol  and  convoying  ships,  by 
day  and  by  night;  and  the  large  Zeppelins  are 
used  in  night  bombing  attacks  and  in  naval  op- 
erations. 

In  France,  Russia,  Italy,  Germany,  and  Aus- 
tria, there  are  military  dirigibles,  differing  in 
form  from  the  naval  dirigibles.  In  Great 
Britain  all  the  dirigibles  are  in  the  navy. 

The  United  States  was  one  of  the  first  coun- 
tries to  build  a  dirigible  for  military  purposes. 
Bids  were  invited  in  1907-08  for  a  dirigible  for 
the  army. 


Rigid,  Semi-Rigid,  and  Non-Rigid  Dirigibles 

Three  types  of  dirigibles  have  been  used  by 
the  European  countries:  (1)  the  rigid;  (2)  the 
semi-rigid;  (3)  the  non-rigid. 

(1)  The  rigid  type  of  dirigible  is  one  in 
which  the  shape  of  the  gas  compartments  is 
maintained  by  means  of  rigid  framework,  such 
as  the  Zeppelins  and  Shiitte  Lanz.     For  de- 


ls: 


The  French  dirigibles  of  the  Lebaudy  class  are 
examples  of  the  semi-rigid  type. 

(3)  The  non-rigid  dirigibles  depend  en- 
tirely on  gas  pressure  within  the  envelope  to 
maintain  shape;  the  nacelle  being  suspended  by 
net  of  longitudinal  canvas  bands  sewed  to  the 
envelope.  Dirigibles  having  a  long  rigid 
framework  nacelle  suspended  some  distance  be- 
low the  envelope  are  usually  included  in  the  non- 
rigid  class.  The  Beachy  airship  and  armj^  Di- 
rigible No.  1  (1908)  of  several  years  ago  are 
the  best  known  non-rigid  types  in  this  coun- 
try. 

Military  Observation  Balloons 

When  a  few  years  ago  the  aeroplane  proved 
to  be  successful,  and  the  attention  of  practically 
all  students  of  aeronautics  was  drawn  to  its 
development  for  military  purposes,  interest  in 
the  captive  balloon  as  a  means  of  observation 
waned,  not  only  in  the  United  States,  but 
abroad.  In  our  case,  the  lack  of  sufficient  ap- 
propriations for  the  aeronautical  service  of  the 
army  was  also  largely  responsible  for  our 
failure  to  develop  this  valuable  auxiliary. 

The  present  war  in  Europe  has  demonstrated 
that  the  aeroplane,  while  of  the  greatest  value 
for  aerial  reconnaissance,  is  not  able  to  replace 
the  captive  balloon  for  certain  purposes.  So 
thousands  of  kite  balloons  are  used  in  the  pres- 


ve^rnc/ti.  Sei^Ais  Srifces/teo 


/^yfA/ei/y^/?  y,v^  if^ 


■/fi/'/'//i/ff  ^/r/i/et. 


Sif/£>jr  Ji,  /7/vc  zzo/f  /fa fie  /"aaai  £ 

~Azzcnaff  &  /fofir 

-ff/fSArr 

TTie  Spherical   lialloon — used  mainly  to  train  pilots  for  military  observation   balloons.    The  balloons   range  in  size  from 

30,000  to  80,000  cubic  feet. 


in 


MILITARY  AEROSTATICS 


150 


ent  war  for  directing  artillery  fire  and  observa- 
tion. 

The  great  advantage  of  the  captive  balloon  is 
that  the  observer  is  constantly  in  direct  tele- 
phonic communication  with  the  artillery  com- 
manders in  his  vicinity;  constant  and  thor- 
ough inspection  of  the  enemy's  positions  with 
the  aid  of  powerful  glasses  and  telescopes 
reveals  every  movement  of  bodies  of  troops 
or  anything  new  that  has  appeared  during 
the  previous  niglit,  and  the  targets  thus  pre- 
sented can  be  immediately  taken  under  fire. 
Continuous  and  searching  observation  of  the 
same  sector  enables  an  observer  to  note  even 
slight  changes  in  the  color  of  the  earth  and 
to  make  important  deductions  therefrom. 
Changes  in  trench  construction  can  thus  be 
easily  detected. 

One  observer  on  the  western  battle  front  in 
France  states  that  he  was  able  to  count  twenty- 
six  balloons  in  sight  at  one  time ;  this  is  convinc- 
ing testimony  of  their  extensive  use.  It  is  an 
interesting  development  of  the  present  war  that 
battle  type  aeroplanes  ai'e  assigned  for  the  pro- 
tection of  the  captive  balloons  and  for  this  pur- 
pose cruise  about  at  a  height  of  several  thousand 
feet  above  the  balloon,  ready  to  swoop  down 
upon  any  enemy  aeroplanes  that  attempt  to 
destroy  it. 

Frequently,  anti-aircraft  guns  are  located 
sufficiently  near  balloons  to  maintain  barage 
fire  over  them  to  prevent  hostile  aeroplanes 
from  approaching  within  range  of  their  in- 
cendiary rockets  or  bullets. 

The  spherical  type  of  captive  balloon  has  been 


abandoned  in  favor  of  the  elongated  type,  often 
referred  to  as  "sausage"  or  "drachen"  (German 
for  kite)  balloon,  since  the  latter  type  has 
much  greater  steadiness  in  the  winds;  the  pres- 
sure of  the  moving  air  against  the  under  side  of 
the  balloon  holds  it  steady  in  the  same  manner 
as  in  the  case  of  the  common  paper  kite. 

The  kite  balloon  is  fitted  with  a  tail  consisting 
of  several  conical  canvas  cups,  to  assist  in  main- 
taining its  stability,  with  the  same  result  as  is 
secured  by  affixing  a  tail  to  the  toy  kite.  The 
latest  type  of  captive  balloons  are  made  with 
stream  line  shape  and  fins  so  that  the  kite  tail- 
cups  are  not  required  for  steadiness,  and  conse- 
quently should  not  properly  be  referred  to  as 
kites. 

Employed  at  Night  as  Well  as  in  the  Daytime 

In  Europe  the  observation  balloons  are 
placed  from  two  to  four  miles  in  rear  of  the  line 
of  trenches,  and  are  separated  by  intervals  de- 
pending upon  the  artillery  activity  in  various 
sectors.  The  altitude  at  which  they  are  held 
is  dependent  upon  the  atmospheric  condi- 
tions and  upon  the  distance  of  the  enemy's 
artillery.  They  are  usually  sent  up  at  daylight, 
and  remain  in  the  air  until  dark,  being  drawn 
down  every  few  hours  to  change  observers. 
Occasionally  they  remain  up  at  night,  and  it  is 
frequently  found  that  enemy  guns  that  are  not 
visible  by  daylight  may  be  located  at  night  by 
their  flashes.  Even  after  dark  it  has  been 
found  that  observers  who  have  studied  every 
feature  of  the  ground  for  days  are  able  to  see 


The  winch  for  the     kite-balloon  mounted  on  a    ^7? 
truck. 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


One  of  the  new  Cacquou  type  observation  balloons  used  exten- 
sively by  the  Allies. 

enough  to  fix  accurately  the  position  of  the 
flashes.  The  strain  of  constant  observation 
with  high-power  glasses,  or  telescopes  makes  it 
advisable  to  change  the  observers  at  frequent  in- 
tervals. 

It  is  customary  to  have  two  officers  in  the  car 
of  the  balloon,  and  they  are  connected  with  the 
ground  by  telephone.  One  method  is  to  have 
an  insulated  telephone  wire  in  the  center  of  the 
cable  which  holds  the  balloon;  another  method 
is  to  drop  a  strong,  light-weight  wire  from  the 
basket  of  the  balloon  to  connect  with  the  tele- 
phone circuits  directly  underneath.  In  both 
cases  the  steel  wires  of  the  holding  cable  serve 
to  complete  the  electric  circuit  for  the  tele- 
phones. 

Balloon  companies  are  provided  with  tele- 
phone switchboards  so  that  the  observer  in  the 
basket  can  communicate  directly  with  any  bat- 


tery or  higher  artillery  commander  in  his  vi- 
cinity. 

Buildings,  hills,  or  specially  constructed 
towers  concealed  by  the  trees  are  frequently 
utilized  in  conjunction  with  captive  balloons  to 
provide  an  auxiliary  observing  station,  so  that 
the  two  may  serve  as  the  end  stations  of  a  base 
line  for  the  accurate  location  of  targets.  In 
some  cases  another  balloon  is  used  as  the  second 
observing  station. 

For  Directing  Artillery  Fire 

It  has  been  learned  that  at  the  beginning  of 
the  war  various  special  codes  of  signals  were 
experimented  with  for  the  purpose  of  enabling 
observers  to  report  the  error  in  the  fall  of  shots, 
but  these  have  been  discontinued  in  favor  of  the 
brief  annoimcement  of  "over,"  "short,"  "right," 
and  "left."  Field  glasses  having  a  milled  scale 
permit  of  the  observer  reporting  in  degrees  the 
distance  of  shots  from  the  target. 

For  service  with  the  mobile  army  it  was  cus- 
tomary in  Europe  before  the  war  to  have  highly 
trained  balloon  companies,  able  to  inflate  a  bal- 
loon and  have  it,  with  its  observers,  several 
thousand  feet  in  the  air  in  about  twenty  min- 
utes after  the  organization  had  halted;  this 
speed  was  attained  by  using  compressed  hy- 
drogen carried  in  special  vehicles. 

Hydrogen  Supply  and  the  "Nurse" 

The  information  of  three  or  more  years  ago 
indicated  that  the  peace  strength  of  the  balloon 
companies  in  Europe  averaged  about  sixty  men. 
The  arduous  and  continuous  service  that  has 
been  required  during  the  war  has  necessitated 
an  increase  in  the  number,  there  being  at  the 
present  time  in  some  cases  160  officers  and  men 
assigned  to  one  balloon;  this  number  pro- 
vides for  three  reliefs  for  the  captive  balloon, 
the  observation  tower  personnel,  the  telephone 
switchboard  operators,  and  details  for  the 
manufactiH-e  of  hydrogen. 

Since  the  service  along  the  western  battle 
front  has  been  in  the  nature  of  siege  warfare,  it 
has  been  practicable  to  supply  hydrogen  from 
portable  field  generators,  instead  of  furnishing 
it  compressed  in  cylinders. 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


161 


The  average  capacity  of  the  balloon  is 
32,000  cubic  feet.  There  is  continuous  loss  of 
hydrogen  due  to  leakage  through  the  fabric  and 
to  losses  from  expansion  at  high  altitudes ;  these 
losses  are  ordinarily  replaced  at  night.  A  com- 
mon method  of  replacing  gas  is  to  fill  small  bal- 
loons called  "nurses"  at  the  nearest  field  gen- 
erating plant;  a  small  detachment  of  men  can 
easily  conduct  this  supply  balloon  to  the  hangar 
and  transfer  hydrogen  from  the  "nurse"  to  the 
captive  balloon  as  it  may  be  required. 

The  Windlass 

The  most  modern  tj^pe  of  windlass  for  hold- 
ing captive  balloons  consists  of  a  winding  drum 
constructed  on  a  motor  truck. 

Whenever  enemy  aircraft  attempt  to  destroy 
a  captive  balloon,  it  is  customary  to  haul  it 
down  rapidly  or  to  keep  it  moving  around  the 
field,  to  lessen  the  chances  of  its  being  hit.  The 
moving  is  often  done  by  using  twenty-five  or 
more  men,  each  having  a  rope  attached  to  a 
snatch  block,  through  which  the  cable  is  passed. 
These  men  then  walk  to  various  points  in  the 
field,  and  their  movement  changes  the  position 
of  the  balloon  not  only  horizontally  but  verti- 
cally as  well. 

Captive  balloons  are  occasionally  destroyed 
by  incendiary  bullets,  arrows,  or  bombs  dropped 
by  aviators.     Destruction  in  this  maimer  is  not 


necessarily  fatal  to  the  observers,  as  they  are 
usually  provided  with  parachutes  attached  to 
body  harness,  which  permit  their  safe  descent  to 
the  ground. 

About  eight  years  ago,  while  Fort  Omaha 
was  garrisoned  by  signal  corps  troops  only,  a 
large  balloon  hangar  was  constructed  at  that 
point,  together  with  a  plant  for  generating  hy- 
drogen by  the  electrolysis  of  water  and  the  ma- 
chinery for  compressing  the  gas.  After  its 
completion,  the  equipment  was  used  for  about 
two  years  for  free  and  captive  balloon  instruc- 
tion, but  its  employment  for  this  purpose  was 
later  discontinued  for  the  reasons  previously 
stated. 

The  U.  S.  Army  Balloon  School  is  now  estab- 
lished at  Fort  Omaha.  Commissioned  and  en- 
listed personnel  are  assembled  there,  organ- 
ized into  companies  and  squadrons,  provided 
with  equipment  and  given  considerable  train- 
ing before  being  sent  out  to  serve  the  artillery 
and  divisions. 

Free  Balloon  Training  Necessary 

In  case  the  cable  holding  a  captive  balloon 
should  break,  it  then  becomes  necessary  for  the 
observer  to  descend  and  land  in  the  same  man- 
ner as  in  manoeuvering  the  ordinary  free  balloon, 
for  which  reason  an  essential  part  of  the  prelim- 
inary training  of  students  at  the  Balloon  School 


One  of  the  American  Blimps  manufactured  by  the  Goodrich  Company.  (Passed  by  the  Censor.) 


III 


^»MJL^  ^ 


162 


MILITARY  AEROSTATICS 


168 


consists  in  the  navigation  of  free  balloons  and 
qualifying  as  pilots  thereof. 

The  Free  Balloons 

ITS   CONSTRUCTION,   INFLATION,  AND   OPERATION 

The  present  war  has  brought  out  the  value  of 
free  balloon  training,  and  the  sportsmen  who 
took  up  ballooning  as  a  sport  in  the  past  twelve 
years  are  now  as  valuable  to  the  cause  of  na- 
tional preparedness  as  if  they  had  had  military 
training  for  that  same  length  of  time. 

A  free  balloon  is  the  simplest  of  all  aircraft. 
It  is  essentially  a  spherical  bag  made  of  silk,  or 
cotton  varnished  or  rubberized  to  prevent  too 
rapid  diffusion  of  the  contained  gas.  Coal  gas 
of  light  density  (4)  and  hydrogen  are  the  gases 
ordinarily  used  for  the  inflation  of  spherical  bal- 
loons. A  net  is  spread  over  the  spherical  gas 
envelope  and  by  means  of  a  loading  ring  the 
basket  for  passengers  is  attached  to  the  lower 
terminal  ropes  of  the  net. 

In  the  top  of  the  envelope  is  a  manceuvering 
valve  the  opening  of  which  permits  the  escape 
of  gas  and  consequent  descent  of  the  balloon. 
The  valve  cord,  usually  white  in  color,  hangs 
vertically  passing  down  through  the  appendix 
opening  within  reach  of  the  pilot.  When  a  free 
balloon  lands  in  a  wind  it  is  necessary  to  deflate 
it  veiy  quickly  in  order  to  avoid  being  dragged 
along  the  ground ;  to  provide  for  this  a  special 
ripping  panel  is  made  into  the  upper  surface  of 
the  envelope,  so  arranged  that  when  the  pilot 
pulls  the  cord  (colored  red)  attached  to  the  up- 
per end  of  this  panel  the  stitching  rips,  thereby 
opening  several  feet  of  the  gas  bag  and  empty- 
ing all  gas  in  a  few  seconds. 

A  free  balloon  usually  is  provided  with  a  long 
guide  rope  and  anchor  (with  separate  rope). 
The  navigating  instruments  consist  of  a  record- 
ing barometer  (baragraph)  calibrated  for  alti- 
tude measurements,  a  statoscope,  which  is  also 
a  sensitive  barometer  and  will  indicate  changes 
in  altitude  of  only  six  or  seven  feet. 

Synopsis  of  the  Course  of  Training  at  United 
States  Army  Balloon  School 

The  course  of  technical  training  is  both  prac- 
tical and  theoretical,  so  arranged  that  the  prac- 


One   ot    till-   first  kite-balloons   used   by  the  Aerostatic  Section, 
U.  S.   Army   at   Omatia.     (Photo  passed  by  the  censor.) 

tical  instruction  will  have  preference  at  all  times 
when  weather  conditions  are  suitable.  When- 
ever high  winds  or  rain  interfere  with  the  out- 
door training  the  class  room  instruction  is 
held  and  consists  principally  of  conferences. 
The  instructor  covers  the  subject  thoroughly 
and  students  are  expected  to  ask  questions  and 
join  freely  in  discussion.  Practical  instruction 
in  the  measurement  of  density  of  gases, 
testing  and  adjustment  of  instruments  and  sim- 
ilar laboratoiy  indoor  work  is  conducted 
when  weather  conditions  outside  are  unfavor- 
able. 

PRACTICAL   INSTRUCTION 

Generation  and  compression  of  hydrogen. 

Hydraulic  testing  of  gas  cylinders. 

Spreading  envelopes  and  assembling  parts  of 
free  and  captive  balloons. 

Inflation  of  balloons. 

Balancing  free  balloons. 

Use  of  ballast  and  balloon  instruments  while 
on  voyages. 

Selection  of  landing  spots  and  drag-roping. 

Deflation  by  valve  and  rip  panel. 

Folding,  packing,  and  shipment  of  bal- 
loons. 


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One  of  hundreds  of  Kite  Balloons,  which  serve 
as  the  eyes  of  the  artillery  on  all  the  fronts,  be- 
ing towed  by  its  mooring-rope  to  its  anchorage. 
There  is  a  Kite  Balloon  for  every  heavy  gun. 
An  account  of  how  Kite  Balloons  are  operated 
for  artillery  was  given  in  "Flying"  for  Decem- 
ber. 


Replacing  of  rip  panel,  repairs  and  inspec- 
tion of  envelope  and  net. 

Qualification  as  balloon  pilot  according  to 
F.  A.  I.  rules. 

Testing  of  cordage  and  fabric  for  breaking 
strength. 

Testing  of  fabric  for  permeability  to  gases. 

Practical  handling  of  captive  balloon  wind- 
lass. 

Filling  kite  balloons  rapidly  from  cylinders 
of  compressed  hydrogen. 

Motor  truck  operation  and  maintenance. 

Determining  course  and  position  of  free  bal- 
loon by  use  of  maps  and  compass. 

conferences:  obganization,  equipment  and 
training  of  balloon  companies 

Assignment  of  duties,  commissioned  and  en- 
listed personnel. 

Transportation  and  special  technical  vehicles. 

Replacing  gas  lost  by  diffusion  and  expan- 
sion. 

Replacement  of  empty  hydrogen  cylinders. 

Field  hydrogen  generators. 

Field  compressing  outfits. 

Meth(Mls  of  observing  and  indicating  targets 
and  plotting  shots. 

Telephone  sen-ice  from  balloons,  instniments 
and  circuits. 


Photography  and  sketching  from  balloons. 
Visual  signal  codes  from  balloons. 
Property  damage  caused  by  descent  in  free 
balloons. 

conferences:  balloon  construction 

Kinds  of  fabric  suitable  for  balloons. 

Preparation  and  application  of  varnishes  for 
cotton  balloons. 

Cordage  for  nets  and  suspensions. 

Shapes  of  balloon  envelopes  and  standard 
sizes. 

Strip  and  panel  construction  for  envelopes. 

Laying  out  patterns  for  envelopes. 

Various  types  of  seams. 

Designs  and  tests  of  suspension  patches. 

Manufacture  of  nets. 

Tj'pes  and  sizes  of  manoeuvering  valves  and 
pressure  valves. 

Size,  location,  cord  attachment  and  replace- 
ment of  rip  panel. 

Appendix  ring,  neck  and  cord. 

Kite  balloon  steering  bags  and  substitutes. 

Number,  size  and  shape  of  tail  cups. 

Strength,  weight,  flexibility  and  construction 
of  cable  for  captive  balloons. 

Sizes,  types,  weight  and  attacliment  of  bal- 
loon cars. 

Essential  features  of  concentrating  rings. 


MILITARY  AEROSTATICS 


165 


conferences:  gases 

Kinds  of  gas  suitable  for  free,  captive  and 
dirigible  balloons. 

Specific  gravity  of  gases  and  methods  of  de- 
termining. 

Manufacture  of  coal-gas  and  water-gas. 

Production  of  hydrogen  by  electrolysis  of 
water. 

Hydrogen  by  steam  and  iron  method. 

Hydrogen  by  compression  and  refrigeration 
method. 

Hydrogen  by  decarburation  of  oils. 

Hydrogen  by  silicon-soda  process. 

Hj'drogen  from  hydrogenite  and  hydrolythe. 

Testing  hydrogen  for  purity. 

Compression  of  gases. 

Flow  of  gases  through  pipes  and  orifices. 

Types  of  gas-holders  and  their  maintenance. 

conferences  :  meteorology 

Indicating  and  recording,  barometers,  ther- 
mometers, hygrometers  and  anemometers. 

Tests,  maintenance  and  method  of  mounting 
instruments. 


Various  changes  in  atmosphere  with  increas- 
ing altitude. 

Movement  of  high  and  low  pressure  areas; 
direction  and  rate  at  various  seasons. 

Movement  of  atmosphere  over  large  areas. 

Local  effect  of  vertical  currents. 

Cloud  formations  and  deductions  from 
them. 

Weather  maps,  weather  predictions;  storm 
warnings  and  weather  signal  codes. 

Tornadoes  and  cyclones;  seasons  and  locali- 
ties. 

Average  wind  velocity  in  sections  of  the 
United  States. 

conferences:  dirigible  balloons 

General  types  of  rigid,  semi-rigid  and  non- 
rigid  balloons,  and  employment  of  each  type. 

Rigid  dirigibles :  Dimensions,  shapes  and  ma- 
terials used. 

Semi-rigid:  Dimensions,  shape,  materials, 
important  structural  features  and  methods  of 
car  suspension. 

Non-rigid:   Dimensions   and   shapes;   main- 


Drawing  reproduced   fruiii  the  "lllublraled  Lumlun  News,"  showing  the  extent  of  the  employment  of  observation  balloons  on  the 

Somme  front. 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


taining  shape;  material  for  envelopes;  methods 
of  ear  suspension. 

Air  resistance  to  various  shapes  and  skin  re- 
sistance. 

Size  and  arrangement  of  ballonets. 

EmplojTnent  of  ballast. 

Vertical  and  horizontal  stabilizing  fins. 

Rudders  for  altitude  and  direction. 

Xumber  and  arrangement  propellers. 

Gasoline  engines  suitable  for  dirigibles. 

Number  and  distribution  and  sizes  of  motors. 


Gas  engine  principles  and  maintenance. 

Dj'namic  reaction  of  atmosphere  on  under 
surface. 

Velocity  with  respect  to  wind  direction  and 
earth. 

Na\  igating  instruments. 

Hangars  and  methods  of  entry  and  exit  in 
wind. 

Designs  for  descending  on  water  or  land. 

Bomb  dropping  devices. 

Armament. 


Memoranda: 


This  pliotogrui)h,  passed  by   Uic  censor, 


shows  one  of  the  hangars  and  some  of  the  balloons  at  liie   L.  cj.  Army  Balloon  School  at 
Omaha,  Nebraska.     (International  Photo.) 


CHAPTER  XIII 

HYDROGEN  FOR  MILITARY  PURPOSES 

Notes  Prepaked  by  Lieut.-Colonel  C.  DeF.  Chandler,  Signal  Corps,  U.  S.  A.,  for  Army 

Balloon  School 


The  production  of  hydrogen  for  commercial 
purposes  has  naturally  been  toward  the  develop- 
ment of  methods  which  insure  low  cost,  and  the 
equipment  designed  is  usually  for  permanent 
installations.  Greatest  efficiency  in  the  pro- 
duction of  hydrogen  for  the  military  service  in- 
volves processes  which  permit  of  easily  trans- 
portable generating  equipment,  ample  avail- 
able supplies  of  chemical  substances,  and  purity 
of  gas.  It  is  often  practicable  for  the  army  to 
use  hydrogen  plants  of  commercial  types,  ship- 
ping the  gas  compressed  in  cylinders,  so  that  it 
is  important  that  officers  assigned  to  the  lighter- 
than-air  service  become  familiar  with  all  prac- 
ticable methods. 

Properties  of  Hydrogen 

Hydrogen  is  a  colorless  and  odorless  gas, 
when  pure.  Frequently  in  the  manufacture  of 
hydrogen  by  chemical  processes  impurities  in 


materials  cause  combinations  of  sulphur,  carbon 
and  arsenic,  which  with  hydrogen  even  in  mi- 
nute quantities,  produces  an  odor  often  incor- 
rectly referred  to  as  that  of  hydrogen. 

Hydrogen  is  the  lightest  known  gas,  having 
a  density  of  .0696,  referred  to  air  at  the  same 
pressure  and  tempei'ature ;  this  is  equivalent  to 
a  weight  of  .005621  pounds  per  cubic  foot  at 
temperature  of  zero  degrees  C,  and  76  cm. 
(.001476  grams  per  cubic  centimeter,  at  zero  de- 
grees C.  76  cm.).  1  Gram  (15.43  grains)  at 
0°  C.  76  cm.  equals  11.11  liters  equivalent  to 
678  cubic  inches  of  hydrogen.  One  grain  of 
hydrogen  at  60°  F.  and  30  inches  barometric 
pressure  equals  46.45  cubic  inches. 

Compared  to  other  gases,  hydrogen  is  ab- 
sorbed very  slightly  in  water.  At  0°  C,  the  ab- 
sorption in  water  is  .00192  and  at  80  degrees  C, 
the  absorption  is  .00079  referring  to  weight 
in  grams  H2  absorbed  in  1000  grams  of  water. 
Hydrogen  becomes  liquid  at  a  temperature  of 


167 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


A   British  airship  about  to  ascend. 

minus  220  degrees  C.  when  subjected  to  a  pres- 
sure of  20  atmospheres.  No  matter  how  low 
the  temperature,  the  pressure  must  be  at  least 
14  atmospheres,  and,  at  this  critical  pressure, 
hydrogen  liquefies  at  minus  240.8  C. 

The  coefficient  of  expansion  of  hydrogen  due 
to  temperature  changes  is  .00366  per  degree 
Centigrade  at  a  pressure  of  100  centimeters  of 
mercury,  and  between  the  temperature  of  1°  and 
100°  Centigrade.  This  coefficient  of  expansion 
should  be  particularly  noted  for  the  reason  that 
in  less  than  24  hours  changes  in  temperature  of 
72°  F.  (40°  C.)  in  the  north  temperate  zone  are 
not  unusual.  A  lowering  of  the  temperature 
40°  C.  reduces  the  volume  of  gas  nearly  15  per 
cent,  causing  a  balloon  of  25,000  cubic  feet 
capacity  to  become  flabby  and  have  the  appear- 
ance of  losing  3200  cubic  feet  of  gas. 

Boyle's  Law  states  that  for  a  constant  tem- 
perature the  volume  of  gas  diminishes  in  direct 
proportion  to  the  pressure,  but  this  applies  only 
to  ideal  gases,  of  which  there  are  none.  The  di- 
vergence of  actual  gases  from  Boyle's  Law  does 
not  follow  any  formula ;  a  curve  plotted  for  any 
one  gas  is  irregular  at  various  pressures.     ( See 


Smithsonian  Physical  Tables.)  Hydrogen  is 
less  compressible  than  indicated  by  Boyle's  Law, 
while  nearly  all  other  gases  are  more  compress- 
ible. At  normal  temperatures  and  a  pressure 
of  2000  pounds  per  sq.  inch  (136  atmospheres), 
the  quantity  of  free  hydrogen  in  commercial 
cylinders  of  2640  cubic  inches,  should  be,  accord- 
ing to  Boyle's  Law,  208  cu.  ft.  whereas  experi- 
ments show  only  191  cu.  ft.  (Bureau  of  Stand- 
ards.) 

Hydrogen  will  burn  in  air  when  the  percent- 
age is  as  low  as  4i/4,  the  flame  traveling  upward 
when  ignited  below.  As  the  percentage  of  H2 
increases  to  9,  the  flame  will  travel  downward 
or  in  any  direction.  Further  increases  in  per- 
centage H2  increase  the  intensity  of  the  flame 
propagation,  which  when  very  rapid  and  violent 
is  called  an  explosion.  The  flame  propagation 
is  increased  when  the  hydrogen  is  mixed  with 
oxygen  not  diluted  with  nitrogen  as  in  air.  Ex- 
amples of  this  power  and  effect  are  occasionally 
observed  when  hydrogen  and  oxygen  are  acci- 
dentally compressed  in  the  same  cylinder. 

Vitriol  Process 

One  of  the  oldest  and  best  known  methods  for 
hydrogen  production  is  the  vitriol  process. 
The  action  of  sulphuric  acid  on  iron,  or  zinc 
evolves  hydrogen  as  shown  by  the  following 
chemical  equation: 

Fe  +  H2SO4  Aq  =  FeS04  +  2H 

It  is  essential  that  dilute  acid  be  used  for  the 
reason  that  concentrated  sulphuric  acid  forms  a 
film  of  sulphate  of  iron  on  the  surface,  which 
is  soluble  in  water  but  not  dissolved  by  the  con- 
centrated acid.  This  process  is  so  well  kno^^^l 
that  a  detailed  description  here  seems  unneces- 
sary. The  generating  equipment  can  often  be 
improvised  by  using  substantial  barrels  or  vats 
of  wood  or  large  glass  or  earthenware  carboys, 
and  lead  pipes  for  conducting  tlie  acid.  The 
caution  to  always  pour  the  acid  into  the  water 
and  never  the  water  into  concentrated  acid  can 
not  be  repeated  too  often.  Furthermore,  when 
using  improvised  equipment  or  even  specially 
constructed  generators  that  are  not  positively 
gas  tight,  never  strike  a  match  or  carry  an  open 
light  such  as  a  lantern  near  the  generators. 


HYDROGEN  FOR  MILITARY  PURPOSES 


169 


It  is  found  in  practice  that  the  washing  and 
purifying  of  the  gas  by  the  usual  methods  does 
not  entirely  remove  the  water  vapor  carrying 
traces  of  sulphuric  acid,  which  is  most  injurious 
to  rubberized  balloon  fabrics ;  for  this  reason  the 
vitriol  process  is  not  favored  when  it  is  prac- 
ticable to  secure  hydrogen  by  other  processes, 
but  if  it  must  be  used  then  special  precautions 
should  be  taken  such  as  multiplying  the  number 
of  washers  and  purifiers  and  frequently  chang- 
ing the  lime  in  the  purifiers.  Fresh  unslaked 
lime  is  used  in  the  purifier  to  absorb  the  moisture 
charged  with  traces  of  sulphuric  acid  which 
passes  out  of  the  hot  generating  tanks.  The 
lime  (CaO)' has  a  great  affinity  for  water  (CaO 
-(- H2O  ^  Ca  (011)2)  changing  it  to  slaked 
lime  (calcium  hydroxide)  upon  absorbing  the 
water.  The  lime  also  combines  chemically  with 
the  sulphuric  acid   forming  calcium   sulphate 

(2CaO  +  H2SO4  =  CaSO,  +  Ca(0H)2). 

Greater  purity  of  hydrogen  can  be  insured 
when  the  weight  of  apparatus  is  unimpor- 
tant, as  in  permanent  installations,  by  add- 
ing in  series  more  purifiers  containing  chemical 
substances  such  as  Caustic  Soda  (NaOH)  and 
Calcium  Chloride  (CaCl2)  both  of  which  have 
property  of  absorbing  moisture  which  is  carried 
along  with  the  hydrogen. 

In  order  to  determine  the  quantities  of  chem- 
icals required  to  produce  a  certain  quantity  of 
hydrogen  by  any  jjrocess,  apply  the  atomic 
weights  of  the  elements  in  the  chemical  equa- 
tions in  the  manner  shown  below;  for  example. 


making  the  object  of  the  computation  1000  cu. 
ft.  of  hydrogen,  it  is  necessary  to  determine  first 
the  number  of  cubic  feet  of  hydrogen  in  one 
pound  of  the  gas.  This  is  found  to  be  about 
178  feet  by  taking  12.388  cu.  ft.  of  air  as  weigh- 
ing one  pound  and  considering  air  as  14.4  times 
heavier  than  hydrogen,  which  figures  are  suffi- 
ciently accurate  for  this  purpose. 

Example :     Fe  +  H2SO4  =  FeSO*  +  H2 
55.84  (2  +  32  +  64)=  152  +  2 

Then  by  Proportion: 

3256  cu.  ft.  H  :  1000  cu.  ft.  ::  55.84  lbs.  Fe,  :  X 
X  =  157  lbs.  iron 

Similarly  for  sulphuric  acid,  356  :  1000  : :  98  X 
X  =  275  lbs. 

It  is  seen  from  the  foregoing  that  157  lbs.  of 
iron  and  275  lbs.  sulphuric  acid  are  theoretically 
required  to  produce  1000  cubic  ft.  hydrogen,  but 
in  estimating  or  purchasing  these  materials  it  is 
always  advisable  to  increase  the  amounts  by  at 
least  5  and  better  10  per  cent,  to  allow  for  im- 
purities in  chemicals,  incomplete  chemical  ac- 
tion, and  losses  of  gas  due  to  generators  and 
pipes  not  being  gas-tight  in  improvised  ap- 
paratus. 

The  atomic  weight  of  zinc  is  65  and  by  a  sim- 
ilar chemical  equation  it  is  found  that  theoreti- 
cally 182.5  lbs.  of  zinc  and  275  lbs.  of  sulphuric 
acid  are  required  to  produce  1000  cubic  feet  of 
hydrogen. 


i 

tkiSiitiSmh&fii 

"I 

L .--^^ 

jrMr 

1^6^^  '.jfe^i^MitoWaisSfcai 

Wm 

finS'^  inii  d?9inK3 

JiKqoiBfi 

BmlSra 

The  motor  transports,  including  hydrogen  carriers  of  a   U.  S.  Army  balloon  company  photographed  at  Umaha.     (Passed  by  the 

Censor.) 


170 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Portable  hydrogen  gas  plant  constructed  for  the  chief  engineer- 
ing department  of  the  Imperial  Russian  War  OfBce. 


Zn  +  HoS04   .  Aq==ZnS04  .  Aq  +  2H. 

65+(2  +  32  +  64)  =  (65  +  32  +64) +2. 

At  least  5  per  cent,  should  be  estimated  above 
the  theoretical  amounts,  for  supplies  of  zinc  and 
acid.  Zinc  usually  contains  some  lead  as  im- 
purity; the  lead  is  not  objectionable,  but  on  the 
contrary,  is  said  to  assist  in  promoting  rapid 
chemical  combination  due  to  galvanic  action. 

Using  only  the  quantities  of  iron  and  acid  ac- 
cording to  the  theoretical  computation  and  as- 
simiing  the  cost  of  iron  turnings  at  2  cents  per 
pound  and  acid  at  3  cents  per  pound,  the  cost  of 
materials  alone  to  produce  1000  cu.  ft.  hydrogen 
would  be  $11.39. 

Electrolytic  Method 

Hydrogen  of  greatest  purity  is  obtained  in 
commercial  practice  by  the  electrolysis  of  water, 
the  hydrogen  collecting  on  the  negative  elec- 
trode and  the  oxygen  on  the  positive  electrode 
where  current  enters  the  cell.  A  direct  current 
of  electricity  is  passed  through  water  in  a  suit- 
able cell  which  is  provided  with  pipes  for  col- 
lecting both  gases.  The  electro-chemical  equiv- 
alent of  hydrogen  is  .0000104  grams  per  cou- 
lomb which  in  larger  units  amounts  to  nearly  15 
cubic  feet  of  hydrogen  for  a  current  of  1000 
ampere  hours.  The  theoretical  electromotive 
force  required  to  dissociate  water  into  its  con- 
stituent elements  is  1.47  volts  between  elec- 
trodes. Therefore,  due  to  the  internal  resist- 
ance of  the  cell,  if  the  voltage  required  is  2,  then 
the  computation  shows  that  one  kilowatt  hour  of 


electric  power  will  produce  7^/2  cubic  feet  of 
hydrogen. 

The  internal  resistance  of  cells  increases  with 
the  distance  between  the  electrodes,  and  de- 
creases as  the  size  of  the  electrode  increases.  It 
varies  also  depending  upon  the  nature  and  spe- 
cific gravity  of  the  electrolyte  in  the  cell. 

Pure  distilled  water  is  a  very  poor  conductor 
of  electricity  and  extremely  high  E.INI.F.  would 
be  necessary  unless  the  conductivitj^  is  improved 
by  adding  suitable  chemicals  to  the  water.  Or- 
dinarily, pure  caustic  soda  (NaOH)  is  used, 
bringing  the  solution  to  specific  gravity  between 
1.2  and  1.25  at  60°  F.  It  is  found  experiment- 
ally that  2^/4  pounds  of  chemicallj^  pure  caustic 
soda  are  required  to  bring  one  gallon  of  distilled 
water  to  1.25  specific  gravity.  This  is  about  17 
per  cent,  caustic  soda  and  is  the  point  at  which 
the  solution  has  the  greatest  conductivity. 
Adding  more  caustic  soda  increases  the  internal 
resistance.  Caustic  potash  (KOH)  may  also 
be  used  for  electrolyte  but  larger  quantity  is  re- 
quired and  the  present  cost  is  much  greater  than 
that  of  caustic  soda. 

There  are  two  general  types  of  construction 
for  electrolizers,  one  being  the  unit  type  which 
consists  of  separate  cells,  each  containing  the 
positive  and  negative  electrodes,  connected  elec- 
trically in  series;  the  other  general  type  being 
called  by  various  names,  "bi-polar,"  "multiple- 
plate,"  and  "filter-press"  types.  These  electro- 
lizers are  usually  constructed  by  assembling 
large  plates  very  close  together  separating  the 
positive  and  negative  electrodes  by  sheets  of  as- 
bestos; where  110  volt  power  is  available  these 
generators  have  60  pairs  of  plates.  The  ad- 
vantage of  the  multiple  plate  type  over  the  unit 
cell  type  is  principally  lower  first  cost  and  less 
floor  space  required;  the  disadvantages  being 
in  greater  maintenance  cost  and  difficulty  of 
preventing  leakage  of  gas.  ^lost  of  the  electro- 
lizers made  in  the  United  States,  both  unit  type 
and  bi-i)olar,  utilize  a  special  weave  of  asbestos 
cloth  as  separator  for  the  hydrogen  and  oxygen 
within  the  cell.  The  foreign-made  cells  at  Fort 
Omaha  have  a  very  fine  wire  gauze  to  separate 
the  gases. 

The  quantity  of  hydrogen  produced  by  this 
method  is  proportional  to  the  amjjerage  passed 


HYDROGEN  FOR  MILITARY  PURPOSES 


171 


through  the  cell.  For  American  made  electro- 
lizers  the  current  varies  from  35  amperes  to 
1000  amperes,  and  for  the  Siemens  cells  at  Fort 
Omaha  the  normal  current  is  1500  amperes. 
The  E.  M.  F.  required  for  each  unit  cell  or  for 
one  pair  of  plates  in  the  multiple  type  will  aver- 
age 2  volts,  but  depends  entirely  upon  the  in- 
ternal resistance  of  the  cell,  which  in  turn  de- 
pends upon  the  size  of  the  electrodes,  distance 
between  them,  nature  and  specific  gravity  of  the 
electrolyte  and  the  temperature.  It  is  observed 
in  practice  that  in  starting  the  plant  when  cells 
are  cold  the  E.M.F.  per  cell  is  often  more  than 
3I/2  volts,  which  reduces  to  less  than  2  volts  after 
the  cells  become  hot. 

As  the  water  in  the  cells  is  converted  into  gas, 
it  must  be  replaced  by  pure  distilled  water. 
The  quantity  being  5.76  gallons  for  1000  cubic 
feet  of  hydrogen.  It  is  seldom  necessary  to  add 
caustic  soda  to  the  solution  and  then  only 
enough  to  replace  the  very  small  quantity  which 
is  carried  off  from  the  cells  by  the  moisture  with 
the  hot  gases,  but  even  this  vapor  may  be  con- 
densed and  recovered  to  some  extent  by  mois- 
ture traps  of  various  kinds. 

Most  manufacturers  of  electrolizers  in  the 
United  States  claim  an  output  of  7V2  cubic  feet 
of  hydrogen  per  kilowatt  hour.  As  shown  in 
the  preceding  paragraphs,  this  means  an  E.  M. 
F.  of  not  to  exceed  2  volts  per  cell.  When  it  is 
possible  to  secure  electric  power  at  1  cent  per 


K.  W.  H.  the  cost  of  1000  cubic  feet  or  hydro- 
gen for  power  alone  is  $1.57  (assuming  motor- 
generator  efficiency  of  85  per  cent.,  and  electro- 
lizer  efficiency  of  7^  cubic  feet  hydrogen  per 
K.  W.  H.). 

The  electrolytic  plant  installed  by  the  armj' 
at  Fort  Omaha  in  1908  consists  of  30  large  cells 
made  by  Siemens  Bros.  Company,  Ltd.,  Lon- 
don, the  normal  current  being  1500  amperes 
and  the  voltage  varying  fi'om  4  to  2.2  per  cell, 
depending  on  temperature.  The  temperature 
should  be  maintained  at  150  degrees  F. 
Higher  than  this  is  likely  to  damage  the  insula- 
tion and  produce  an  excess  of  moisture  with  the 
gas.  Lower  temperature  increases  the  internal 
resistance  and  cost  of  electric  power.  Each  cell 
produces  23.3  cubic  feet  of  hydrogen  per  hour, 
a  total  of  699  cubic  feet  per  hour  for  the  30 
cells,  equivalent  to  16,776  cubic  feet  per  day 
of  24  hours  for  the  plant. 

Silicol  Process 

The  production  of  hydrogen  by  dropping 
ferro-silicon  into  hot  caustic  soda  is,  in  the 
French  and  British  Armies,  known  as  the 
"silicol"  method;  in  Germany  it  is  called  the 
Schuckert  process,  and  for  manj'  j'ears  the  de- 
tails of  it  were  carefully  concealed. 

The  chemical  reaction  producing  hydrogen  is 
between  silicon  and  caustic  soda  without  any 


•  .f '*t i^.  vl -V -^j^jatSl! .  . 


A  batteiy  of  hydrogen  gas 
cylinders  attached  to  supply 
pipe   of   balloon  being   filled. 


172 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


change  in  the  iron.  The  following  chemical 
equation  will  serve  to  explain  the  process: 
Si  +  2XaOH  +  2H2O  =  NaaSiOs  +  4H.  + 
HoO.  In  Germany  it  was  customary  to  use 
pure  or  nearly  pure  silicon.  In  France  this 
method  was  developed  for  the  military  service 
by  Capt.  Le  Large  and  Dr.  Jaubert ;  the  gene- 
rating apparatus  being  designed  in  three  types ; 
viz:  Auto  truck  transportable  size,  semi- 
fixed and  for  permanent  installations.  Ferro- 
silicon  is  used,  being  more  easily  secured 
and  at  less  cost  than  pure  silicon  as  in 
the  Schuckert  generators.  The  steel  indus- 
try in  this  countrj'  uses  large  quantities  of 
ferro-silicon  containing  50  to  75  per  cent,  silicon. 
Experiments  have  shown  that  more  satisfactory 
chemical  action  is  secured  by  having  the  silicon 
content  80  to  85  per  cent.  Commercial  caustic 
soda  of  97  per  cent.  NaOH  is  suitable. 

Except  in  very  cold  weather  the  mixing  of 
caustic  soda  with  water  produces  sufficient  heat 
to  start  the  chemical  combination  of  silicon  and 
soda.  It  is  necessary  to  agitate  the  solution 
constantly  to  secure  best  results  and  avoid  sud- 
den generation  of  large  quantities  of  gas  of  ex- 
plosive violence.  The  solution  resulting  from 
the  chemical  combination  is  sodium  silicate, 
which  may  be  easily  drawn  off  at  the  bottom  of 
the  mixing  tank. 

According  to  the  chemical  equation,  the  pro- 
duction of  one  thousand  cubic  feet  of  hydrogen 
would  require  39.6  pounds  of  pure  silicon  and 
112.3  pounds  of  pure  caustic  soda.  The  actual 
quantities   which    should   be   supplied   depend 


German  railway  truck  with  itccl  cylinders. 


upon  the  silicon  content  of  the  ferro-silicon  and 
the  percentage  of  purity  of  the  caustic  soda. 
An  experiment  conducted  for  the  army  deter- 
mined that  58  pounds  of  80  per  cent,  ferro-sili- 
con and  125Y2  pounds  caustic  soda  would  pro- 
duce 1000  cubic  feet  hydrogen.  Ferro-silicon 
at  15  cents  per  pound  and  caustic  soda  at  3  cents 
per  pound  would  bring  the  total  cost  for  ma- 
terials to  $12.46  per  1000  cubic  feet. 

Ferro-silicon  may  be  stored  without  deteriora- 
tion by  moisture  and  without  any  special  pre- 
caution for  its  care.  The  caustic  soda  must  be 
protected  from  moisture  and  is  usually  supplied 
in  air-tight  drums  containing  100  pounds. 

In  connection  with  silicol  generators,  there 
are  required  washers  and  purifiers  to  remove 
from  the  gas  the  hot  vapors  carrying  caustic 
soda  solution.  Field  generators  of  this  process 
should  alwaj^s  be  set  up  for  operation  near  a 
stream  or  other  ample  supply  of  water.  It  is 
possible  to  design  the  generating  equipment 
with  radiators  for  cooling  the  circulating  water 
for  situations  where  water  economy  is  important. 

Iron  Contact  Process 

The  iron  contact  process  for  production  of 
hydrogen  is  often  referred  to  as  the  regenera- 
tive steam  and  iron  and  method,  the  principle 
being  that  when  steam  passes  over  red  hot  iron 
it  is  decomposed  into  its  constituent  elements, 
the  iron  absorbing  oxygen  from  the  steam  and 
the  hydrogen  collected.  The  chemical  reaction 
is  represented  by  the  equation :  2Fe  -f  3H2O 
=  Fe203  +  6H.  To  utilize  this  principle 
commercially,  it  is  necessary  to  reduce  the 
ferric-oxide  back  again  to  metallic  iron  which 
can  be  done  by  passing  carbon  monoxide  over 
the  iron  oxide,  the  carbon  monoxide  (CO)  tak- 
ing an  atom  of  oxygen  from  the  iron  becomes 
carbon  dioxide  (COo)  represented  by  the  fol- 
lowing equation: 

SCO  +  FejOs  =  2Fe  +  SCO^ 

The  conmiercial  equipment  for  production  of 
hydrogen  by  the  iron  contact  process  utilizes 
the  well-known  water-gas  process  for  making 
the  carbon  monoxide  which  is  needed  to  reduce 
the  iron  from  the  oxide  to  pure  metallic  state. 


HYDROGEN  FOR  MILITARY  PURPOSES 


173 


Close  view  of  the  carriage  of  a  British 
Blimp. 


The  water-gas  generator  is  filled  with  coke 
which  is  heated  to  redness  by  a  blast  of  air  for 
a  very  brief  period.  When  steam  is  turned  on 
to  this  red  hot  coke,  it  is  decomposed,  the  hy- 
drogen freed  from  the  oxygen  is  combined  with 
the  carbon  of  the  coke  forming  carbon  monox- 
ide (CO).  The  water-gas  consists  principally 
of  hydrogen  and  carbon  monoxide,  but  must  be 
passed  through  washers  and  purifiers  to  remove 
dust  and  particularly  sulphuretted  hydrogen. 
Sulphur  is  removed  by  passing  the  gas  over 
trays  of  iron.  The  purified  water-gas,  usually 
referred  to  as  "blue  gas,"  is  then  stored  in  a 
holder,  available  for  use  as  reducing  agent. 

After  steam  has  passed  over  the  red  hot  iron 
for  a  few  minutes,  the  temperature  is  lowered  to 
such  an  extent  that  it  no  longer  decomposes  the 
steam  and  it  is  then  necessary  to  raise  its  heat 
and  at  the  same  time  change  the  ferric  oxide 
to  metallic  iron  by  turning  the  blue  gas  into  the 
ovens.  The  period  of  heating  the  iron  and  re- 
ducing the  oxide  requires  about  twice  the 
amount  of  time  for  the  hydrogen  production 
phase. 

Temperature  is  a  most  important  factor  and 
must  be  constantly  watched  in  all  phases  of  the 
process.  In  the  water-gas  generator,  if  the 
temperature  is  too  slow,  carbon  dioxide  is 
formed  instead  of  carbon  monoxide.  In  reduc- 
ing the  ferric  oxide,  if  the  temperature  is  not 


sufficiently  high  the  reduction  will  be  only  from 
the  ferric  oxide  FcaOs  to  Fe^Oi  or  at  still  lower 
temperature  to  FeO  instead  of  to  the  pure 
metallic  Fe. 

The  reduction  ovens  are  originally  filled  with 
hematite  (Fe203)  which  should  be  as  porous  as 
possible  in  order  to  expose  greater  surface  to 
the  action  of  the  steam  and  carbon  monoxide, 
and  this  ore  should  be  free  from  sulphur  com- 
pounds and  other  impurities.  It  is  necessary 
to  replace  the  ore  in  the  ovens  about  every  six 
months. 

The  iron  contact  process  was  developed  long 
ago  by  Coutelle  and  perfected  by  Giffard  in 
France,  then  developed  commercially  in  Eng- 
land by  Lane  using  several  retorts  for  the  iron. 
In  Germany  it  was  further  developed  by  A. 
Messerschmitt,  utilizing  one  large  regenerative 
oven  instead  of  many  small  retorts.  The  Mes- 
serschmitt regenerative  oven  is  patented  in  the 
United  States.  The  patents  relate  only  to  the 
oven  and  retorts;  the  steam  and  iron  process  is 
not  patented.  At  least  two  firms  in  this  coun- 
try install  iron  contact  plants,  which  produce 
3500  cubic  feet  of  hydrogen  per  hour.  Plants 
of  this  size  and  type  are  now  under  construction 
for  the  Navy  Department  at  Pensacola,  for  the 
Army  at  Langley  Field,  and  for  a  private  firm 
near  Akron,  Ohio. 

Hydrogen  produced  by  the  iron  contact  proc- 


174 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Filling  cylinders  on   the  railway  truck. 

ess  has  a  purity  of  at  least  98  per  cent.  The 
impurities  consist  principally  of  nitrogen  and 
carbon  dioxide  which  have  no  deleterious  effect 
on  balloon  fabric,  nor  are  these  gases  inflam- 
mable. It  is  claimed  that  hydrogen  can  be  pro- 
duced by  this  process  from  25  cents  to  75  cents 
per  thousand  cubic  feet. 

Aluminum  Caustic  Soda  Process 

During  the  war  between  Russia  and  Japan 
both  armies  used  field  hydrogen  generators  em- 
ploying the  chemical  reaction  of  alkaline  hy- 
drates upon  aluminum.  Sodium  hydrate 
(XaOH)  ordinarily  known  as  caustic  soda,  is 
preferred  to  the  potassium  hydrate  on  account 
of  the  lower  cost  of  the  soda.  The  chemical 
reaction  taking  placfe  is  represented  by  the  fol- 
lowing equation: 

6XaOH  +  2  Al  =  AI2  ( OXa ) «  +  6H 

The  generating  apparatus  was  constructed  in 
two  types,  one  of  small  size  installed  on  vehicles 
for  rapid  transportation,  and  a  larger  size  called 
"semi-fixed."  An  iron  basket  is  filled  with 
aluminum  sqrap,  lowered  into  the  solution  of 
caustic  soda,  the  cover  being  immediately 
clamped  to  make  it  gas  tight.  The  gas  passes 
from  the  generator  to  a  washing  and  cooling  de- 
vice which  removes  the  traces  of  alkaline  matter. 
In  the  generator  the  aluminum  is  attacked  by 
the  sf)da  solution  with  great  energ>',  the  gas  com- 
ing off  rapidly  and  the  liquid  heating  to  the 


boiling  point,  but  as  the  proportion  of  free  soda 
in  the  solution  diminishes,  the  rate  becomes 
slower.  In  order  to  finish  the  gas  production 
without  delay,  the  generator  is  charged  with 
caustic  soda  considerabh^  above  the  theoretical 
requirement. 

According  to  the  theoretical  computation,  it 
is  found  that  to  produce  1000  cubic  feet  of  hy- 
drogen there  are  required  224  pounds  of  caustic 
soda  and  51  pounds  of  aluminum.  With  caus- 
tic soda  at  3  cents  per  pound  and  aluminum  at 
50  cents  per  pound,  the  cost  of  the  one  thousand 
cubic  feet  of  hydrogen  by  this  process  is  $32.22. 
The  actual  quantity  of  materials  to  be  carried 
will  be  considerably  in  excess  of  275  pounds  and 
the  cost  per  thousand  more  than  the  foregoing 
computation  indicates,  on  account  of  the  neces- 
sity for  using  an  excess  of  caustic  soda  and  the 
fact  that  commercial  caustic  soda  contains  im- 
purities, the  most  common  grade  containing  only 
77  per  cent,  sodium  hydrate. 

The  aluminum  and  alkali  method  has  the  ad- 
vantage of  requiring  about  20  per  cent,  less 
weight  of  material  than  the  viti-iol  process  and 
both  materials  being  dry  are  easily  transported 
without  the  especial  care  which  is  necessary  for 
the  transportation  of  sulphuric  acid.  Further- 
more, the  hydrogen  produced  is  of  greater  pur- 
ity, does  not  contain  volatile  hydrocarbons,  nor 
the  dangerous  gases  produced  by  combinations 
of  hydrogen  and  arsenic. 

U.  S.  patent  was  issued  in  September,  1901, 
for  a  modification  of  the  aluminum-caustic-soda 
process.  The  inventor  prepared  the  material 
by  pouring  molten  caustic  soda  into  a  mass  of 
aluminum  in  the  form  of  powder,  filings,  or 
turnings,  which  was  thoroughly  mixed  before 
the  mass  cooled.  This  mixture  of  material 
must  be  kept  in  sealed  containers  to  avoid  de- 
terioration due  to  moisture  in  the  atmosphere. 
When  the  mixed  substance  is  placed  in  water 
the  chemical  reaction  produces  sodium  alumi- 
nate  and  free  hydrogen,  probably  according  to 
the  following  equation : 

2A1  +  2XaOH  +  xH^O  =  NasAljO*  + 
xH.O  +  8H2 
or  2A1  +  eXaOH  -f  xH,0 
=  NaeAUOa  +  xHsO  +  8H, 


HYDROGEN  FOR  MILITARY  PURPOSES 


175 


Hydrolithe 

"Hydrolyte"  is  calcium  hydride  (CaHz) 
manufactured  by  heating  pure  metalhc  calcium 
in  retorts  containing  hydrogen.  To  produce 
hydrogen  it  is  only  necessary  to  drop  the  gran- 
ulated hydrolythe  into  water.  Generating 
equipment  similar  to  the  ordinary  acetylene  gas 
outfits  are  suitable.  The  reason  hydrolythe  is 
not  more  extensively  used  is  on  account  of  its 
high  cost.  About  ten  years  ago  the  Signal 
Corps  purchased  a  sufficient  quantity  to  con- 
duct experiments,  which  confirmed  all  claims 
for  it,  but  chemical  manufacturers  in  the  United 
States  do  not  produce  it  at  present.  It  will  be 
seen  from  the  following  chemical  equations  that 
only  59  pounds  of  hydrolythe  are  required  to 
produce  1000  cubic  feet  of  hydrogen: 

CaH2  +  H2O  =  CaO  +  4H. 

At  80  cents  per  pound  for  hydrolythe  the  cost 
of  1000  cubic  feet  of  hydrogen  by  this  method 
would  be  $47.20. 

Pure  sodium  or  lithium  dropped  in  water  will 
produce  hydrogen  and  it  is  possible  to  make 
hydrides  of  lithium  the  same  as  calcium  which 


will  similarly  produce  hydrogen  upon  contact 
with  water.  On  account  of  the  light  weight  of 
lithium  this  would  be  particularly  desirable  for 
field  hydrogen  generation,  and  experiments  are 
now  in  progress  to  determine  whether  it  is  prac- 
ticable to  manufacture  lithium  hydride  at  rea- 
sonable cost. 

Dropping  pure  lithium  in  water  would  the- 
oretically require  only  40  pounds  to  produce 
1000  cubic  feet  of  hydrogen:  2Li  +  H2O  = 
Li^O  +  2H. 

And  of  lithium  hydride  221/2  pounds  would 
produce  1000  cubic  feet  hydrogen  2LiH  + 
H.O  =  LiaO  +  4H. 

About  ten  years  ago  an  American  manufac- 
turer proposed  the  use  of  lead  compounds  hav- 
ing great  affinity  for  water  known  as  "Hydrone 
A,  B,  and  C,"  and  experiments  were  conducted 
by  the  Signal  Corps.  It  developed  that  the 
chemical  reaction  upon  dropping  the  substance 
into  an  alkaline  solution  was  so  violent  that  the 
oxygen  of  the  air  above  the  generating  tank 
would  burn  the  hydrogen, — the  ignition  being 
due  to  heat  of  the  chemical  action.  This  diffi- 
culty was  overcome  by  manufacturing  a  lower 
grade   which   evolved   hydrogen   slowly.     The 


One    of    the    Goodyear    "Blimps."    Photo    passed    by    the    Censor. 


176 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


y 


A  military  balloon  ascending. 

low-grade  material  was  first  dropped  into  the 
generator  until  the  escaping  gas  had  carried 
with  it  all  oxygen  above  the  water,  then  the 
high-grade  substance  was  fed  into  the  generator. 
On  account  of  the  extreme  care  that  was  neces- 
sary to  avoid  explosions  with  this  method  and 
the  considerable  weight  of  the  hydrone,  its  fur- 
ther development  for  field  hydrogen  generation 
in  the  army  was  discontinued.  One  pound  of 
hydrone  produced  only  2.88  cubic  feet  hydro- 
gen at  a  cost  of  QYo  cents  per  foot. 


Hydrogenite 

This  hydrogen  process  is  a  modification  of 
the  "silicol"  process  already  described.  The 
chemical  substances  and  reaction  are  the  same 
as  the  silicol,  but  the  materials  are  prepared 
and  used  in  somewhat  different  manner.  Pul- 
verized ferro-silicon  and  caustic  soda  properly 
proportioned  are  thoroughly  mixed  and  pre- 
served in  hermetically  sealed  cartridges,  each 
containing  .50  kilograms. 

The  field  generators  to  use  these  cartridges 
consist  of  metal  container  slightly  larger  than 


the  cartridge,  having  a  lid  which  can  be  clamped 
down  gas  tight.  After  placing  the  cartridge  in 
the  apparatus,  the  top  of  the  can  is  opened  and 
the  mixed  powders  ignited.  Around  the  inside 
of  the  cylindrical  burning  oven  in  which  the 
cartridge  is  placed,  is  a  trough  to  contain  a 
measured  quantity  of  water.  The  heat  pro- 
duced by  the  burning  of  the  chemicals  quickly 
converts  this  water  into  steam,  the  silicon,  soda, 
and  water  combining  as  in  the  previously  shown 
equation  describing  silicol  method. 

Ignition  may  be  started  by  a  fuse  or  taper  in- 
serted in  the  powder  or  by  placing  on  top  a 
small  quantity  of  some  easily  combustible 
powder  in  order  to  produce  sufficient  heat  in 
one  spot  to  start  the  combustion.  The  hydro- 
genite burns  rapidly  and  without  flame,  like 
tinder;  a  cartridge  of  50  kilograms  being  con- 
sumed in  about  ten  minutes. 

When  the  mixture  is  first  ignited,  the  air  in 
the  chamber  and  products  of  combustion  are 
permitted  to  escape  until  the  pure  hydrogen  ap- 
pears. The  gas  is  passed  through  washing  and 
cooling  purifiers  before  being  used. 

It  is  learned  that  even  with  the  greatest  care 
generators  ai'e  frequently  destroyed  by  explo- 
sions, for  which  reason  the  process  is  not  in  gen- 
eral use. 

Hydrogen  from  Water-Gas 

A  German  chemist  developed  and  advocated 
some  years  ago  the  production  of  hydrogen  for 
aeronautical  purposes  by  first  manufacturing 
water-gas  in  the  usual  manner,  which  consists 
principally  of  hydrogen  and  carbon  monoxide, 
passing  the  water-gas  over  red  hot  calcium  car- 
bide in  the  form  of  powder.  The  hot  calcium 
carbide  decomposes  the  carbon  monoxide  form- 
ing lime  (CaO)  and  leaving  carbon  in  the  form 
of  crystalline  graphite.  The  inventor  claims 
that  minor  impurities  in  the  water-gas  are  al- 
most entirely  removed  in  the  reaction,  produc- 
ing hydrogen  of  99  per  cent,  purity.  The  re- 
port further  stated  that  generating  equipment 
was  devised  to  produce  70,000  cubic  feet  of  hy- 
drogen daily. 

Hydrogen  may  also  be  separated  from  water- 
gas  or  coal  gas  by  the  fractional  refrigeration 


HYDROGEN  FOR  MILITARY  PURPOSES 


177 


process.  Hydrogen  liquefies  under  pressure  at 
lower  temperature  tlian  other  common  gases, 
so  that  from  illuminating  gas  having  a  consid- 
erable percentage  of  hydrogen  it  is  possible  to 
cool  and  compress  it  with  liquid  air  apparatus, 
drawing  off  first  all  other  gases  as  they  liquefy 
and  leaving  the  hydrogen.  This  method  is  not 
in  general  use  for  commercial  production  for 
the  reason  that  other  methods  offer  more  simple 
and  more  economical  means  of  securing  hydro- 
gen. 

The  Electrical  Review  (Vol.  40)  reported 
that  M.  D'Arsonval  passed  coal  gas  previously 
cooled  to  minus  80°  C.  through  a  Linde  liquid 
air  machine,  obtaining  3500  cubic  feet  of  hydro- 
gen per  hour,  expending  12  to  15  horse-power. 
Assuming  coal  gas  to  cost  $1  per  thousand  and 
containing  50  per  cent,  hydrogen,  the  cost  of 
material  would  be  about  $2  per  thousand  cubic 
feet  hydrogen,  to  which  must  be  added  approxi- 
mately 60  cents  per  thousand  for  power,  plus 
cost  of  expert  attendance. 

Aluminum-Potassium  Cyanide  Process 

A  French  chemist  a  few  years  ago  advocated 
the  generation   of  hydi'ogen  for   aeronautical 


purposes  by  mixing  aluminum  filings  with  pul- 
verized bichloride  of  mercury  and  potassium 
cyanide.  After  these  ingredients  are  thor- 
oughly mixed  hydrogen  will  be  produced  by 
adding  water.  The  powder  has  a  density  of 
1.42  and  must  be  kept  in  hermetically  sealed 
cans.  It  is  stated  that  experiments  indicated 
187  pounds  of  this  material  were  required  to 
produce  1000  cubic  feet  of  hydrogen.  The 
chemical  reactions  which  take  place  should 
properly  be  represented  by  three  or  four  stages, 
but  may  be  sufficiently  explained  by  the  follow- 
ing single  equation: 

6KCN  +  6H2O  +  4A1  +  3  HgCla  = 
2K3AIO3  +  12H  +  3Hg(CN)2  +  2A1C18 

Acetylene  Process 

In  1901  Mr.  H.  Houbon,  a  resident  of  Eng- 
land, invented  and  patented  a  process  for  mak- 
ing pure  hydrogen  from  acetylene.  He  com- 
pressed the  acetylene  to  5  atmospheres  in  a 
Caillet  steel  bomb  and  ignited  it  by  electric 
spark.  The  carbon  precipitates  in  the  form  of 
fine  soot  leaving  the  pure  hydrogen.  It  is 
stated  that  the  process  is  without  danger  and 


A    British    "Blimp"    passing  over    an    anti-aircraft    post. 


178 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


calcium  carbide  for  producing  acetylene  is  very 
cheap,  but  it  is  not  known  that  this  process  has 
ever  been  perfected  for  producing  hydrogen  in 
large  quantities  for  aeronautical  service. 

By  computation  it  is  found  that  180  pounds 
of  calcium  carbide  are  required  to  produce  1000 
cubic  feet  of  hydrogen  by  this  method. 

C2H2  +  Heat  =  2C  +  2H 

Iron  and  Water  Process 

Recently  an  article  in  a  German  technical 
journal  described  a  new  method  for  securing 
compressed  hj'drogen  of  great  purity.  So  far 
as  known  it  has  been  employed  only  in  labora- 
tories, but  it  may  be  developed  later  on  a  com- 
mercial scale. 

Powdered  iron  is  mixed  in  water  in  a  vertical 
steel  cylinder,  the  liquid  being  subjected  to  a 
pressure  of  300  atmospheres  (5,410  pounds  per 
square  inch)  and  the  temperature  raised  to  350° 
C.  The  chemical  reaction  that  takes  place  is 
sufficiently  explained  by  the  following  equa- 
tion : 

2Fe  +  3H2O  =  Fe^Os  +  6H 

from  which  it  is  seen  that  under  this  great  heat 
and  pressure  the  iron  combines  with  the  oxygen 
from  the  water,  and  the  hydrogen  may  be  re- 
moved at  the  top  of  the  cylinder  already  com- 
pressed for  storage  in  cylinders.  The  iron  ox- 
ide may  be  easily  reduced  again  to  metallic  iron, 
which  is  facilitated  by  its  porous  condition,  due 
to  the  peculiar  manner  in  which  it  is  oxidized. 
Hydrogen  obtained  is  said  to  have  99  per  cent, 
purity,  which  can  be  further  increased  to  99.95 
per  cent,  by  being  passed  over  charcoal.  When 
iron  contains  sulphur,  the  sulphur  is  not  at- 
tacked, but  any  carbon  content  in  the  iron  is 
converted  into  carbon  monoxide. 

Silico-Acetylene  Process 

The  silicides  of  calcium,  barium  and  stron- 
tium (CaSi2  :  BaSi2  :  SrSi2)  are  made  in  the 


electric  furnace  similar  to  the  manufacture  of 
calcium  carbide.  When  calcium  silicide  is 
added  to  aciduated  water,  it  is  decomposed, 
leaving  sihco-acetylene  in  solution;  the  calcium 
oxide  is  precipitated.  The  solution  is  drawn 
off  and  evaporated,  leaving  yellow  ciystals  of 
sihco-acetylene  SiaHa.  When  these  crystals 
are  added  to  alkahne  solution  such  as  caustic 
soda  or  potash,  the  silico-acetylene  is  decom- 
posed, evolving  hydrogen.  It  is  reported  that 
163  pounds  of  silico-acetylene  are  required  to 
produce  1000  cubic  feet  of  hydrogen. 

Decarburation  of  Oils 

About  four  years  ago  the  Scientific  American 
described  equipment  developed  by  the  German 
Army  for  the  generation  of  hydrogen  by  the 
method  of  decarburizing  hydro-carbon  oils. 
The  apparatus  was  designed  for  installation  on 
two  railway  cars,  the  main  part  of  the  equipment 
consisting  of  two  gas  producers.  To  fire  up 
these  producers  to  the  proper  heat  requires  from 
one  to  two  hours. 

The  producers  are  filled  with  coke  which  is 
heated  to  redness  by  air-blast.  Crude  petro- 
leum or  any  petroleum  distillates  are  first  va- 
porized and  then  passed  through  the  producer 
ovens  containing  the  hot  coke,  which  decom- 
poses the  oil.  After  about  twenty  minutes  the 
coke  has  been  reduced  in  temperature  so  much 
that  it  is  necessary  to  heat  it  again  to  redness 
by  hot  air  blast.  This  requires  only  two  or 
three  minutes. 

The  gas  produced  is  passed  through  water 
scrubbers  and  purifiers  to  remove  sulphur.  It 
contains  considerable  carbon  monoxide  which 
is  removed  by  passing  the  gas  through  an  oven, 
the  details  of  which  process  are  not  stated.  The 
resultant  gas  is  said  to  be  OS.!  per  cent,  hydro- 
gen, 1.2  per  cent,  nitrogen,  and  0.4  per  cent, 
carbon  monoxide,  and  to  have  a  specific  gravity 
between  0.087  and  0.092. 


Courtesy  Underwood   &  Underwood. 
Group   of   students   seated   around   big   relief   map. 


Photo  passed  by  the  Censor. 


CHAPTER  XIV 

TRAINING  AVIATORS  FOR  THE  UNITED  STATES  ARMY;  HOME  AND 

FOREIGN  SERVICE 


The  training  of  aviators  for  the  United  States 
Army,  for  home  and  foreign  service,  is  con- 
ducted by  the  Organization  and  Training  Sec- 
tion of  the  Aviation  Division,  Signal  Corps, 
whose  offices  are  in  the  War  Department, 
Washington,  D.  C. 

According  to  a  recently  issued  official  state- 
ment, this  Section  deals  with  the  organization 
of  aviation  school  squadrons  and  standard 
aerosquadrons,  the  latter  composed  of  gradu- 
ated Reserve  jSIilitary  Aviators. 

There  are  but  a  few  officers  with  the  title 
"Military  Aviator  "  and  "Junior  Military  Av- 
iator."    These  are  in  administrative  positions. 


This  Section  has  nothing  to  do  with  training 
of  men  for  aerostatic  work,  which  is  handled  by 
the  Balloon  Division. 

The  Aviation  Division  of  the  Signal  Corps 
is  composed,  originally,  of  officers  and  enlisted 
men  of  the  Regular  Army,  limited  by  law  to  a 
definite  number.  Additional  personnel  is  pro- 
vided through  the  Signal  Officers'  Reserve 
Corps,  the  Signal  Enlisted  Reserve  Corps,  and 
the  employment  of  civilians  in  instructive,  ad- 
visory, administrative,  or  other  capacities. 

Civilians  may  be  employed  (1)  as  such;  (2) 
by  passing  standard  physical  and  mental  ex- 
aminations and  by  going  through  the  routine 


Practically  the  entire  new  flying  personnel  is     of  joining  the  Signal  Officers'  Reserve  Corps, 
to  be  composed  of  Reserve  Military  Aviators,     in  which  event,   if  satisfactory,  they  may  be 


179 


180 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


given  commissions  therein  commensurate  in 
grade  with  their  attainments  and  duties,  as  fol- 
lows: 

(a)  Non-flj'ing  duty, 

(b)  Flying  duty  (as  pilots  or  observers), 

(c)  By  enlistment  in  the  Signal  Enlisted 
Reserve  Corps. 

The  Organization  and  Training  Section  also 
handles  original  applications  for  commissions 
in  the  S.O.R.C.  from  civilians.  Regular 
Army  or  National  Guard  officers  and  men  are 
needed  as  supply,  engineer,  or  field-inspector 
officers.  Opportunity  is  afforded  by  personal 
interview  to  obtain  first-hand  knowledge  of  the 
particular  attainments  of  each  man.  If  pre- 
liminary investigation  is  satisfactory,  the  ap- 
plicant fills  out  his  blank  and  is  turned  over  to 
the  Personnel  Division,  which  attends  to  the 
routine  of  physical  and  mental  examination. 
Upon  the  obtaining  of  his  commission  he  is  as- 
signed to  such  place  as  his  services  are  required. 

Form  of  letter  of  application  for  examination 
for  commission  in  Officers'  Reserve  Corps. 

[Under  section  37,  Act  of  June  3,  1916.] 


I  have  served 


years  in 


19- 


To 


Sir:  I  have  the  honor  to  apply  for  examina- 
tion for  a  commission  as  ^ aviation  section, 

in  the  Signal  Officers'  Reserve  Corps,  organized 
under  the  authority  of  Congress. 

1  Insert  grade,  first  lieutenant,  captain,  or  major. 


I  have  pursued  a  regular  course  of  instruc- 


tion for 


years  m 


I  graduated  in  the  year 


from 


after  having  creditably  pursued  the  course  of 
military  instruction  therein  provided. 

I  was  born  ,  ,  at  ,  and 

am   "• a   citizen   of   the   United   States. 

A.g&    .     Color    .     Height    . 

Weight . 


My  business  is . 

My  experience  is . 

I  inclose  letters  of  recommendation  and  ad- 
dresses of  three  citizens  who  know  me  as  fol- 
lows : . 

Respectfully, 


Permanent  post  office  address 


The  correctness  of  the  statements  above  made 

was  sworn  to  and  subscribed  before  me 

,  19—. 


The  duties  of  the  Aero-Personnel  Division 
consist  of  matters  affecting  the  commissioned 
and  enlisted  men  of  the  Aviation  Section  of  the 
Signal  Corps,  which  may  be  more  conveniently 
termed  the  Army  Air  Service.     All  communi- 

2  Insert  service  in  the  Regular  Army  of  the  United  States,  or 
Volunteer  forces  of  the  United  States,  or  Organized  Militia  of 
any  State,  Territory,  or  District  of  Columbia;  also  state  in  what 
capacity. 

s  Insert  name  and  location  of  the  school  or  college. 

*  Insert  the  name  and  location  of  the  educational  institution. 

5  Insert  "not"  if  in  accordance  with  fact. 

8  Oath  to  be  taken  before,  and  signature  to  be  made  by,  officer 
authorized  by  law  to  administer  oaths. 


Group  of  army  aviation  students  at  one 
of  the  training  fields. 


TRAINING  AVIATORS  FOR  UNITED  STATES  ARMY 


181 


students  learning  the  assembling  ot   aeroplanes  at  a  University,  somewhere  in  America 


cations  to  the  Chief  Signal  Officer,  or  higher 
authority,  that  are  concerned  with  the  subject 
of  aviation  personnel  must  pass  through  this 
Division,  except  when  such  communications 
deal  with  civilian  employees. 

The  personnel  of  the  Army  Air  Service  com- 
prises the  following  groups: 

(a)  Enhsted  men  of  the  Regular  Army. 

(b)  Signal  Enlisted  Reserve,^  throughout 
this  chapter  referred  to  as  "Enlisted  Reserve 
Proper." 

(c)  Men  (flying  duty)  enlisted  temporarily 
in  the  Signal  Enlisted  Reserve  in  order  to  ob- 
tain training  for  a  commission  in  the  Aviation 
Section  of  the  Signal  Officers'  Reserve  Corps. 
(Throughout  this  chapter  they  are  referred  to 
as  the  "Enhsted  Reserve.") 

(d)  Reserve  Officers   (flying  duty). 

(e)  Reserve  Officers    (non-flying  duty). 

(f)  Officers  (of  the  Regular  Army). 

The  Aero-Personnel  Division  is  also  con- 
cerned with  two  other  groups  of  men : 

(g)  Enlisted  applicants  of  the  Regular 
Army  for  transfer  to  the  Air  Service. 

(h)  Commissioned  applicants  of  the  Regular 
Army  for  detail  to  the  Air  Service. 

(a)  Present  provisions  in  regard  to  the  first 
of  these  groups  continue  as  now  prescribed  by 
law  and  Army  Regulations.  The  Aero-Per- 
sonnel Division  has  charge  of  the  records  of  en- 
listed men  of  the  Regular  Army. 

(b)  The  purpose  of  the  "Enlisted  Reserve 
Proper"  has  been  to  secure  a  body  of  trained 

1  Inasmuch  as  all  enlistments  are  for  the  period  of  the  war 
and  the  policy  of  the  office  is  to  accept  men  for  the  Regular 
Army  only,  paragraph  (b)  is  modified  to  this  extent. 


mechanicians,  machinists,  electricians,  chauf- 
feurs, and  other  qualified  men,  who  may  be 
quickly  called  in  time  of  need.  Cards  giving 
the  home  addresses  and  information  about  the 
enlistments  of  such  reservists  are  kept  in  the 
Aero-Personnel  Division.  Similar  informa- 
tion is  in  the  service  record  of  each  reservist,  in 
the  hands  of  the  department  commander  in 
whose  territorial  jurisdiction  he  resides.  No 
more  enlistments  in  this  group  as  reservists  are 
being  made  at  present,  there  being  no  desirabil- 
ity during  wartime  to  increase  the  number  of 
reserves  not  on  active  duty.  At  date  of  writing 
the  entire  personnel  of  this  group  is  being  called 
into  active  service  by  department  commanders 
immediately  upon  enlistment.  They  are  as- 
signed to  aviation  stations  and  placed  in  train- 
ing. 

(c)  The  enlisted  reservists  who  are  appli- 
cants for  commissions  as  reserve  officers,  flying 
duty,  and  are  enlisted  in  the  Signal  Enlisted  Re- 
serve Corps  simply  for  the  purpose  of  prelimi- 
nary training  prior  to  receiving  their  commis- 
sions, comprise  an  extremely  important  group. 
From  their  number  will  come  almost  exclusively 
the  aviators  of  the  Army  Air  Service.  The 
procedure  in  regard  to  the  enlistment  of  these 
men  is  in  the  hands  of  the  Aero-Personnel  Di- 
vision. All  applicants  for  commission  in  the 
Aviation  Section  of  the  Signal  Officers'  Reserve 
Corps  must  forward  their  applications  to  the 
Aero-Personnel  Division  for  approval  or  disap- 
proval. If  the  application  is  approved,  its 
sender  is  given  an  examination  to  determine  his 
physical  condition,  and  a  second  examination  to 
test  his  moral,   professional,   and   educational 


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qualifications  for  a  commission.  Boards  to  give 
the  complete  examinations  are  situated  at  each 
of  the  Schools  of  ^lilitary  Aeronautics;  also  at 
the  several  Signal  Corps  flying  schools  in  the 
different  states  and  at  Washington. 

If  the  candidate  is  successful  in  passing  these 
examinations,  he  is  reexamined  with  a  view  to 
enlistment  as  first-class  private  in  the  Signal 
Enlisted  Reserve,  and  is  then  either  sent  home 
with  a  certificate  of  enlistment  to  await  further 
orders,  or  is  sent  immediately  to  one  of  the 
"ground  schools"  (Schools  of  Military  Aero- 
nautics) for  instruction. 

From  this  time  until  the  receipt  of  his  commis- 
sion the  candidate  is  under  the  jurisdiction  of: 
First,  the  Schools  of  Military  Aeronautics  Di- 
vision; and  later  the  Organization  and  Train- 
ing Division.  The  Aero-Personnel  Division 
asks  for  the  transfer  to  the  "ground  schools"  of 
suitahle  students  on  duty  at  the  Federal  Re- 
serve Officers'  Training  Camps.  Such  re- 
quests, if  recommended,  are  made  weekly. 

(d)  Upon  successful  completion  of  the  fly- 
ing-school course,  the  candidate  is  commissioned 
as  a  reserve  officer,  whereupon  his  relation  to  the 
Aero-Personnel  Division  becomes  like  that  of 
a  regular  officer  of  the  Air  Service. 

Competent  civilian  flyers,  who  pass  the  physi- 
cal and  mental  examinations  and  are  satisfac- 
tory otherwise,  may  at  once  be  commissioned  in 
the  Signal  Officers'  Reserve  Corps  and  ordered 
to  active  duty. 

(e)  Civilian  apj)licants  for  commissions  in 
the  S.  O.  R.  C.  for  non-flying  duty  in  capacities 
such  as  engineer,  supply  or  other  officer,  may 
take  mental  and  physical  examinations  (the  lat- 
ter less  rigid  than  that  for  flying  duty),  and  if 
qualifications  are  satisfactory,  may  be  commis- 
sioned and  ordered  to  active  duty. 


America's  future  airmen  are  here 
shown  ]iracticing  tlie  Morse  Interna- 
tional Code  as  one  of  tlie  first  steps  in 
masterinjr  the  science  of  radio  transmis- 
sion which  they  will  soon  he  using  over 
the  German  trenches  in  France.  Photo 
passed   hy  Censor. 


(f)  All  communications  in  regard  to  officers 
of  the  Arm}'  Air  Service  pass  through  the 
Aero-Personnel  Division.  Similarly,  all  orders 
for  officers  of  the  Air  Service  that  are  requested 
from  the  Adjutant-General  pass  through  this 
division.  Complete  military  records  of  officers 
are  also  kept  there. 

(g)  Applications  of  enlisted  men  of  the  Sig- 
nal Corps  proper,  or  of  other  staff  corps  or  de- 
partments or  arms,  for  transfer  to  the  Air  Serv- 
ice should  be  approved  by  the  Aero-Personnel 
Division  before  orders  are  issued  for  such  trans- 
fer. 

(h)  Any  officer  of  the  Regular  Army,  who  is 
an  applicant  for  detail  to  the  Air  Service,  has  his 
military  record  and  correspondence  concerning 
him  kept  by  the  Aero-Personnel  Division  while 
he  is  undergoing  training  at  the  Signal  Corps 
flying  schools.  Upon  detail  to  the  Air  Service, 
the  status  of  such  an  officer  in  relation  to  this 
division  is  precisely  like  that  of  other  officers  of 
the  Army  Air  Service. 

In  all  cases  application  for  enlistment,  trans- 
fer, detail,  or  commission,  is  made  direct  to  the 
Aero-Personnel  Division. 

Schools  of  Military  Aeronautics 
(Ground  Schools) 

Successful  candidates  for  flying  duty  are  di- 
rected by  the  Aero-Personnel  Division  to  one  of 
the  ground  schools  located  at  the  following  in- 
stitutions : 

Massachusetts  Institute  of  Technology,  Bos- 
ton, Mass. 

Cornell  University,  Ithaca,  New  York. 

Ohio  State  University,  Columbus,  Ohio. 

University  of  Illinois,  I''"rbana.  Illinois. 

Texas  University,  Austin,  Texas. 


TRAINING  AVIATORS  FOR  UNITED  STATES  ARMY 


188 


One  of  the  Army  aviation  training  fields,  showing  Curtis  JN-4  scJiool  planes.    (Committee  on  Public  Information.) 


University  of  California,  Berkeley,  Calif. 

Princeton  University,  Princeton,  N.  J. 

Georgia  Institute  of  Technology,  Atlanta, 
Ga.,  Jolm  Hopkins  University,  etc. 

(Additional  institutions  are  being  added  to 
this  list  at  date  of  writing.) 

Upon  arrival,  the  S.  M.  A.  Division  is  advised 
thereof,  with  a  list  of  candidates,  which  list  is 
kept  by  the  S.  M.  A.  Division  in  cooperation 
with  the  Organization  and  Training  Section. 
Now  the  students  are  under  the  charge  of  the 
S.  M.  A.  Division, 

Here  the  students  serve  eight  weeks  with  the 
pay  of  a  first-class  private,  about  a  dollar  a  day, 
and  with  the  allowance  of  a  dollar  a  day  for 
rations.  Quarters  are  provided  in  barracks. 
The  candidate  upon  entering  the  Ground 
Schools  of  Military  Aeronautics  becomes  a  ca- 
det. He  is  assigned  to  a  "Junior  Squadron," 
where  he  remains  for  three  weeks;  then  he  is 
transferred  to  a  "Senior  Squadron." 

Each  squadron  consists  of  between  twenty  to 
thirty  cadets  in  charge  of  a  first  sergeant. 

At  these  ground  schools  the  cadets  are  given 
a  general  course  in  military  discipline  and  drill, 
as  well  as  intensive  instruction  in  aeronautical 
engines,  telegraphy,  machine-guns,  bombing 
and  fighting,  aerial  observation  and  cooperation 
with  artillery  and  infantry,  including  map- 
reading,  contact  patrol  and  reconnaissance; 
army  regulations  and  military  subjects;  flying 
with  meteorology,  instruments,  compasses,  pho- 
tography; rigging,  care  and  repair  of  aero- 
planes, engines  and  cameras.  Guns  and  other 
apparatus  are  provided  for  practical  study. 


Upon  completion  of  this  course  the  students 
are  assigned  through  the  Aero-Personnel  Di- 
vision to  the  aviation  school  squadrons,  as  noted 
under  "Organization  and  Training." 

The  daily  schedule  at  the  ground  schools  of 
military  areonautics  is  more  or  less  as  follows: 

Reveille,  5 :35  a.  m.  First  call,  5 :40.  All 
calls  are  by  bugles,  the  same  as  in  the  army. 
Assembly  is  blown  at  5 :50  A.  M.,  when  all  cadets 
must  be  in  ranks  in  their  respective  places.  On. 
all  assembly  calls  the  first  sergeant  of  each 
squadron  orders  his  men  to  fall  in.  Then  he 
receives  his  corporal's  report  of  "lates"  or  "ab- 
sentees," about  faces  to  the  officer  of  the  day, 
and  reports  concerning  lates  or  absentees  from 
his  squadron;  whereupon  the  officer  of  the  day 
commands  the  senior  first  sergeant  or  cadet  cap- 
tain to  take  charge  of  the  men  for  calisthenics. 

The  senior  cadet  sergeant  marches  all  the 
squadrons  to  the  court,  and  when  they  have 
taken  their  respective  places  leads  them  through 
ten  minutes  of  calisthenics.  At  the  end  of  this 
time  the  squadrons  are  placed  in  command  of 
their  respective  sergeants,  the  two  senior  squad- 
rons being  marched  immediately  to  mess,  the  re- 
maining squadrons  returning  to  the  quadrangle, 
awaiting  their  turn  for  mess. 

The  mess  takes  about  an  hour  for  each  squad- 
ron. At  6 :55  A.  M.  first  call  for  drill  is  blown. 
At  7  A.  M.  assembly  is  blown,  whereupon  the 
men  are  marched  to  the  drill  field  and  given  one 
hour  of  military  drill.  As  the  men  in  this 
school  are  training  to  become  aviator  officers,  a 
full  course  in  military  drill  is  not  required,  the 
reason  being  that  the  man  getting  his  commis- 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


sion  wiU  have  hardly  any  enhsted  men  under 
him  to  drill. 

Saturday: 

8-9           A.  M. 

9-10 
10-11 

Study  Hour 

Reconnaissance 

Map-Reading 

The  work  after  drill  is  different  for  different 

11-12 

Art  of  Observation 

wings  of  the  school. 

The  first  three  weeks,  or 

For  the  second  week  it  is  as  follows: 

Jimior  Wing,  and  the  last  five  weeks,  or  Senior 

Monday: 

8-9          A.  .M 

9-10 

Study  Hour 

Art  of  Observation 

Wing,  have  the  following  schedules: 

10-11 

Map-Reading 

11-12 

Nomenclature 

FIB8T  THREE    WEEKS 

LAST   FIVE    WEEKS 

2-  3:50  P.M. 

Miniature  range 

JUNIOR    WING 

SENIOR   WING 

Tuesday; 

8-9           A.  M. 

Machine-guns 

7-  8  A.  M.  DrIU 

7-  8  A.  M.  Drill 

9-10 

Study  Hour 

8-9      "      Class 

8-  9     "     Class 

10-12          " 

Gasoline  engines 

9-10     "     DrUl 

9-10     "     Class 

2-  2:50  P.M. 

Art  of  Observation 

10-11     "     Class 

10-11      "     Class 

3-  3:50      " 

Instruments,   including   Compasses 

11-12     "     Calisthenics 

11-12     "     Class 

Wednesday 

8-    9           A.  M. 

Study  Hour 

12          M.    Mess 

12          M.    Mess 

9-10 

Reconnaissance 

2-  3  p.  M.  Drill 

2-  3  P.  M.  Class 

10-12          " 

Gasoline  engines 

S-  4     "     Calistiienics 

3-4      "      Class 

2-  3:50  P.M. 

Miniature  range 

*-  5     "     DriU 

4-5     "     Calisthenics 

Thursday: 

8-11            A.  M. 

Rigging  and  Landing  Gear 

5:45  P.M. 

First  Call 

11-12 

Study  Hour 

5:50      " 

Retreat 

2-  3:50  P.M. 

Gasoline  engines 

5:55      " 

Assembly 

Friday: 

8-9           A.  M. 

Tools 

March  to  mess 

9-10          " 

Study  Hour 

7 :55  p.  M. 

School  Call 

10-11 

Machine-guns 

8:55      " 

Dismissed  or  Recall 

11-12 

Art  of  Observation 

9:10      " 

Tatoo 

2-  3:50  P.M. 

Gasoline  engines 

9:15      " 

Roll  Call  in  barracks 

Saturday: 

8-9           A.  M. 

Study    Hour 

9:30      « 

In  bed — and  lights  out 

9-10 
10-11 

Instruments,  including  Compasses 
Wireless 

Every  Saturday  morning 

between   7  and  8  inspection  of  the 

11-12 

Reconnaissance 

entire  student  company  is 

held   under  arms   on   the  drill   field. 

and  is  followed  by  inspection  of  barracks  by  the  commandant. 

During  the  third  week  it  is  as  follows: 

Monday: 

8-10           A.  M. 

10-12 

Gasoline   engines 
Machine-gun  test 

Instruction  in  the  Junior  Wing 

2-  3       p.  M. 
3-4 

Instruments,    including    Compasses 
Study  Hour 

Instruction  in  the  Junior  Wing  consists  of 

Tuesday: 

8-    9           A.M. 

9-10 

Theory   of   Wireless 
Lecture  on  Photography 

elementary  work  in 

wireless,  such  as  sending 

10-11 
11-12          " 

Machine-guns 
Study  Hour 
Miniature  range 

and  receiving,  machine-gun  instruction  and  ma- 

2- 3:50  P.  M. 

chine-gun  theory. 

Wednesday. 

8-9           A.M. 

9-10 
10-11 
11-12 

Study  Hour 

Meteorology 

Astronomy 

Lecture  on  Fighting  In  the  Air 

Instruction  in  the  Senior  Wing 

Thursday: 

2-  3:50  P.M. 

8-9          A.  M. 

Gas-engines 
Study   Hour 

Instruction  for  the  first  week  in  the  Senior  Wing  is  as  follows: 

9-10 
10-11          " 

Instruments,   including   Compasses 

Contact  patrol 

Tools 

MOXDAT:                7-  8          A.  M. 

Drill 

11-12 

8-10 

Wireless 

2-  3:50  P.  M. 

Miniature  range 

10-12 

Gas-engines 

Friday: 

8-  9        A.  SI. 

Study    Hour 

2-  3:50  P.  M. 

Machine-guns 

9-12 

Rigging  and  Landing  Gear 

TUMBOAX:              8-9         A.  M. 

Lecture,  Type  of  Machine 

2-  3       P.  M. 

Signal  Instruction 

9-10           " 

Lecture,  Bombs  and  Bombing 

3-4 

Map-reading 

10-11 

Lecture,  Wireless 

Saturday: 

8-9          A.  M. 

Buzzer  Practice 

11-12 

Lecture,  Theory  of  Flight 

9-10 

Machine-guns 

2-  330  P.M. 

Lecture,  Gasoline  Engines 

10-12 

Bombs  and  Bombing 

Weoxesoay:      8-9        a.m. 

Theory  of  Wireless 

9-10 

Nomenclature 

For  the  fourth  week  it  is  as  follows: 

10-11 

Reconnaissance 

Monday: 

8-9           A.  M. 

Study  Hour 

11-12          « 

Map-Reading 

9-12 

Rigging  and  Landing  Gear 

■     2-  SaO  P.  M. 

Gas-engines 

2-  3:50  P.  M. 

Gasoline  engines 

Thuudat:         8-9       a.m. 

Nomenclature 

Tuesday: 

8-9           A.  M. 

Study  Hour 

9-10 

Study  Hour 

9-10 

Machine-guns 

10-11          « 

Bomlis  and  Bombing 

10-12 

Miniature  range 

11-12 

Machine-guns 

2-  3:50  P.M. 

Gasoline  engines 

2-  2:50  P.  M. 

Wireless 

Wednesday: 

8-10          A.  M. 

Gasoline  engines 

3-  3:40      " 

Theory  of  Wireless 

10-1 1 

Meteorology 

PUDATi                    8-9          A.  M. 

Study   Hour 

11-12 

Photography 

9-10          " 

Art  of  Observation 

2-3       P.  M. 

Radio  and  Wireless 

10-11 

Theory  of  Wireless 

3-4 

Signal    telegraphy 

11-12 

Machine-guns 

TaUlSDATi 

8-9          A.  M. 

Theory  of  Wireless 

9-  S'M  r.  M. 

Gasoline  engines 

9-10 

Theory  of  Sending  and  Receiving 

TRAINING  AVIATORS  FOR  UNITED  STATES  ARMY 


185 


Lieutenant  Montariol, 
French  Flying  Corps,  in- 
structing a  class  of  avia- 
tion students  somewhere 
in  America. 


Thursday: 

10-12 

A.  M. 

2-  3 

P.  M. 

3-  4, 

(t 

Friday  : 

8-10 
10-12 

A.  M. 

2-  4 

P.  M. 

Saturday : 

8-10 

A.  M. 

10-12 

(( 

For  th 

Monday: 

8-  9 

A.  M. 

9-12 

t< 

2-  4 

P.M. 

Tuesday: 

8-11 

A.  M. 

11-13 

t( 

2-  3:50 

P.  M. 

Wednesday: 

8-  9 

A.  M. 

9-10 

n 

10-11 

n 

11-12 

(( 

2-  3:50 

p.  jr. 

Thursday  : 

8-10 

A.  M. 

10-12 

(( 

2-  3:50 

p.  M. 

Friday: 


Saturday : 


8-10 


10-12 

7-  8 


Examination  in  theory  of  Sending 

and  Receiving  Wireless 
Machine-guns 

Instruction  in  Wigwag  and  Sema- 
phore 

Gasoline    Engines 

Examination  in  the  Theory  of 
Flight 

Machine-guns 

Gasoline   Engines 

Examination    in    Gunnery,    includ- 
ing  bombs   and    bombing,   and 
machine-guns 
e  fifth  week: 

Examination  in  Wigwag  and 
Semaphore 

Work  in  the  field  with  a  field  wire- 
less set,  as  used  by  the  United 
States  Army  in  the  field 

Study  Hour 

Sail-making  and  Rope-splicing 

Study  Hour 

Examination  on  the  theory  of  Gas- 
oline Engines 

Study  Hour 

Lecture  on  Magnetos 

Signal  Telegraphy 

Meteorology 

Care  of  machine 

Rotary  gasoline  engines 

Miniature  range  examination 

Transportation  of  machines.  Ver- 
bal examination  on  motor- 
trucks 

Aerial  observation,  which  consists 
of  fighting  in  the  air,  recon- 
naissance and  map-reading 

Engines 

Inspection 


Training  at  Army  Aviation  Schools 

Graduates  of  the  Schools  of  Mihtary  Aero- 
nautics (ground  schools)  are  assigned  through 


the  Aero-Personnel  Division  in  cooperation 
with  the  O.  &  T.  Section,  to  the  various  aviation 
school  squadrons  for  instruction  in  actual  fly- 
ing. From  this  point  on  the  flying  students 
are  in  charge  of  the  O.  &  T.  Section. 

Following  is  a  list  of  the  location  of  aviation 
school  squadrons  organized  and  to  be  organized 
in  the  near  future.  As  time  goes  on,  doubtless 
this  schedule  will  be  extended. 

Mineola,  N.  Y. — Operating. 

Mt.  Clemens,  Mich.  (Selfridge  Field).— 
Operating. 

Fairfield,  O.  (Wilbur  Wright  Field)  .—Op- 
erating. 

Rantoul,  111.   (Chanute  Field). — Operating. 

So.  Mississippi  Valley. — Under  investiga- 
tion. 

San  Antonio,  Tex. — Operating. 

San  Diego,  Calif.^Now  operating. 

Belleville,  111. — Operating. 

One  station  to  be  in  Rocky  Mountain  Re- 
gion. 

Fort  Sill,  Okla.  (advanced  school  operating) . 

At  the  above  schools  training  is  done  with  as 
much  rapidity  as  possible.  At  the  conclusion 
of  from  fifteen  to  twenty-five  hours'  flying,  it 
is  expected  students  will  be  able  to  pass  tests 
for  certificates  as  Reserve  Military  Aviators. 

While  undergoing  this  flying  instruction,  the 


186 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Training  America's  first  thousand  aviators.    The  photo  shows  three  training  aeroplanes  in  the  air  at  one  of  the  training  fields. 


pupil  is  required  to  study  radio,  gunnery,  pho- 
tograph}', motors  and  aeronautical  engineering. 
This  study  is  practical;  the  student  handles  and 
operates  everj'  instrument,  assembling  and  dis- 
assembling engines,  and  does  construction  and 
repair  of  aeroplanes  to  the  extent  that  he  must 
assemble,  disassemble,  line-up,  etc.  In  the 
^nnery  instruction,  for  instance,  the  student 
uses  a  machine  in  which  a  gun  is  mounted  and 
is  given  target  practice  at  objects  moving  in  the 
air. 

Upon  receiving  their  certificate,  these  flying 
students  are  commissioned  as  First  Lieuten- 
ants, Signal  Officers'  Reserve  Corps,  Aviation 
Section,  and  when  on  duty  involving  frequent 
or  continuous  flying,  receive  twenty-five  per 
■cent,  increase  in  pay.  The  base  pay  is  $2,000  a 
year.  When  on  foreign  duty  ten  per  cent,  in- 
crease on  the  base  pay  is  allowed.  Quarters 
are  also  furnished. 

Standard  aero-squadrons  of  the  army  are 
formed  at  the  aviation  school  squadrons.  The 
flying  and  enlisted  personnel  for  these  squad- 
rons is  furnished  from  these  flying  schools. 
The  officers,  of  course,  are  Reserve  Military 
Aviators  by  this  time,  though  some  may  be 
Junior  Military  Aviators.     The  enlisted  men 


are  of  the  Enlisted  Reserve  Corps,  or  of  the 
Regular  Army. 

These  areo-squadrons,  thus  formed,  will  be 
fully  equipped,  save  as  to  aeroplanes,  and  trans- 
ported to  England  or  France  for  advanced 
training. 

These  graduated  aviators  (R.  M.  A.'s)  may 
also  be  sent  to  complete  the  complement  of  areo- 
squadrons  already  in  process  of  formation  or 
partially  filled,  to  be  maintained  at  certain 
points. 

Tests  for  an  Aviator's  Certificate 

In  different  stages  of  training  the  student  or 
mihtary  aviator  may  go  through  tests  and  ob- 
tain the  following  certificates: 

(1)  The  F.  A.  I.  Certificate.  This  is  the 
international  certificate  issued  under  the  rules 
of  the  International  Aeronautic  Federation  by 
the  Aero  Club  of  America.  It  represents  the 
federation  in  the  United  States  and  in  other 
countries  on  the  American  continent  which  do 
not  have  a  national  areo  club  affiliated  with  the 
International  Aeronautic  Federation. 

It  is  necessary  to  have  this  certificate  to  enter 
aeronautic  meets,  and  to  have  records  homolo- 


TRAINING  AVIATORS  FOR  UNITED  STATES  ARMY 


187 


gated  and  accepted  by  the  International  Aero- 
nautic Federation. 

Following  are  the  rules  under  which  F.  A.  I. 
certificates  are  granted  by  the  Aero  Club  of 
America : 

1.  A  person  desiring  a  pilot's  certificate  must 
apply  in  writing  to  the  Secretary  of  the  Aero 
Club  of  America.  He  must  state  in  his  letter 
the  date  and  place  of  his  birth,  and  enclose 
therein  two  unmounted  photographs  of  himself 
about  2^/4  X  21/^  inches,  together  with  a  fee  of 
five  dollars.  In  case  the  applicant  is  a  natural- 
ized citizen  of  the  United  States  he  must  sub- 
mit proof  of  naturalization. 

2.  On  receipt  of  an  application  the  Secretary 
will  forward  it  promptly  to  the  Contest  Com- 
mittee, which,  in  case  of  an  application  for  an 
aviator's  certificate,  will  designate  a  representa- 
tive to  supervise  the  test  prescribed  by  the  In- 
ternational Aeronautical  Federation,  and  will 
advise  the  representative  of  the  name  and  loca- 
tion of  the  applicant  and,  through  the  Secre- 
tary, advise  the  applicant  of  the  appointment 
of  the  representative  to  take  the  test. 

3.  In  case  the  application  is  for  a  spherical 
balloon  or  for  a  dirigible  balloon  pilot's  certifi- 
cate the  applicant  will  be  fully  advised  by  the 
Contest  Committee. 

4.  All  applications  for  aviator's  certificates 
must  reach  the  Secretary  a  reasonable  time  in 


advance  of  the  date  that  the  applicant  may  ex- 
pect to  take  the  required  test. 

5.  No  telegraphic  applications  for  certificates 
will  be  considered. 

Applicants  for  each  class  of  certificate  must 
be  of  the  age  of  18  years,  and  in  the  case  of  dir- 
igible certificates  21  years,  and  must  pass,  to 
the  satisfaction  of  the  properly  designated  rep- 
resentatives of  the  Aero  Club,  the  tests  pre- 
scribed by  the  F.  A.  I.,  as  follows: 

Spherical  Balloon  Pilot's  Certificate 

Candidates  must  pass  the  following  tests: 

(A)  Five  ascensions  without  any  conditions. 

(B)  An  ascension  of  one  hour's  minimum 
duration  undertaken  by  the  candidate  alone. 

(C)  A  night  ascension  of  two  hours'  mini- 
mum duration,  comprised  between  the  setting 
and  the  rising  of  the  sun. 

The  issue  of  a  certificate  is  always  optional. 

Dirigible  Balloon  Pilot's  Certificate 

Candidates  must  be  21  years  of  age. 

They  must  hold  a  spherical  balloon  pilot's 
certificate  and  furnish  proof  of  having  made 
twenty  (20)  flights  in  a  dirigible  balloon  at 
different  dates. 

They  must  also  undergo  a  technical  examina- 
tion. 


A  group  of  aviation  students  at  one  of 
the  army  training  fields. 


188 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


In  case,  however,  the  candidate  does  not  al- 
ready possess  a  spherical  balloon  certificate,  he 
must  have  made  twenty-five  (25)  ascensions  in 
dirigibles  before  he  can  apply  for  a  certificate. 

The  application  for  the  certificate  must  be 
countersigned  by  two  dirigible  balloon  pilots, 
■who  have  been  present  at  at  least  three  of  the 
departures  and  landings  of  the  candidate. 

The  issue  of  the  certificate  is  always  optional. 

Aviator's  Certificate 

1.  Candidates  must  accomplish  the  three 
following  tests,  each  being  a  separate  flight : 

A  and  B.  Two  distance  flights,  consisting 
of  at  least  5  kilometers  (16,404  feet)  each  in  a 
closed  circuit,  without  touching  the  ground  or 
water,  the  distance  to  be  measured  as  described 
below. 

C.  One  altitude  flight,  during  which  a  height 
of  at  least  100  meters  (328  feet)  above  the 
point  of  departure  must  be  attained;  the  de- 
scent to  be  made  from  that  height  with  the 
motor  cut  off.  A  barograph  must  be  carried 
on  the  aeroplane  in  the  altitude  flight.  The 
landing  must  be  made  in  view  of  the  observers, 
without  restarting  the  motor. 

2.  The  candidate  must  be  alone  in  the  air- 
craft during  the  three  tests. 

3.  Starting  from  and  landing  on  the  water 
is  only  permitted  in  one  of  the  tests  A  and  B. 

4.  The  course  on  which  the  aviator  accom- 


plishes tests  A  and  B  must  be  marked  out  by 
two  posts  or  buoys  situated  not  more  than  500 
meters  (547  yards)  apart. 

5.  The  turns  around  the  posts  or  buoys  must 
be  made  alternately  to  the  right  and  to  the  left, 
so  that  the  flight  will  consist  of  an  uninter- 
rupted series  of  figures  of  8. 

6.  The  distance  flown  shall  be  reckoned  as  if 
in  a  straight  line  between  the  two  posts  or 
buoys. 

7.  The  landing  after  the  two  distance  flights 
is  tests  A  and  B  shall  be  made: 

(a)  By  stopping  the  motor  at  or  before 
the  moment  of  touching  the  ground 
or  water; 

(6)  By  bringing  the  aii-craft  to  rest  not 
more  than  50  meters  (164  feet) 
from  a  point  indicated  previously 
by  the  candidate. 

8.  All  landings  must  be  made  in  a  normal 
manner,  and  the  observers  must  report  any  ir- 
regularities. 

The  issuance  of  the  certificate  is  always  op- 
tional. 

Official  observers  must  be  chosen  from  a  hst 
drawn  up  by  the  governing  organization  of 
each  country. 

Hydroaeroplane  Pilot's  Certificate 

The  tests  to  be  successfully  accomplished  by 
candidates  for  this  certificate  are  the  same  as 


An  instructor  enlifthtening  future  air- 
men in  the  intricacies  of  coast  defense. 


TRAINING  AVIATORS  FOR  UNITED  STATES  ARMY 


189 


those  for  an  aviator's  certificate,  except  that 
starting  from  and  landing  on  the  water  is  per- 
mitted in  all  of  the  tests. 


United  States  Army  Preliminary 
Flying  Test 

(a)  Three  sets  of  figures  8  around  pylons 
1600  feet  apart.  In  making  turns  around 
pylons,  all  parts  of  machine  will  be  kept  within 
a  circle  whose  radius  is  800  feet. 

(b)  Stop  motor  at  a  minimum  height  of  300 
feet  and  land,  causing  machine  to  come  to  rest 
within  150  feet  of  a  previously  designated 
point. 

(c)  An  altitude  test  consisting  of  rising  to  a 
minimum  height  of  1000  feet. 

(d)  Glides  with  motor  throttled,  changing 
direction  90°  to  right  and  left. 

Note. —  (a)  and  (b)  may  be  executed  in  one 
flight;  (c)  and  (d)  in  one  flight.  The  same 
rules  apply  in  starting  from  and  landing  on 
water.  Special  attention  will  be  paid  to  the 
character  of  landings  made. 

Report  of  these  tests  will  be  submitted  to  the 
officer  in  charge  of  the  aviation  section,  with  the 
information  as  to  whether  or  not  the  school  will 
complete  the  training  of  the  aviator  through  the 
reserve  military  aviator  stage. 

If  the  preliminary  flying  test  is  passed  satis- 
factorily and  a  candidate  qualifies  in  other  re- 
spects, he  will  be  eligible  for  further  instruction 
to  qualify  as  a  reserve  military  aviator. 


United  States  Army  Reserve  Military 
Aviator  Test 

Reserve  Military  Aviator  Test.     The  reserve 
military  aviator  test  will  be  as  follows : 

(1)  Climb  out  of  a  field  2000  feet  square  and 
attain  500  feet  altitude,  keeping  all  parts  of  ma- 
chine inside  of  square  during  climb. 

(2)  Glides    at    normal    angle,    with    motor 


throttled.     Spirals  to  right  and  left.     Change 
of  direction  in  gliding. 

(3)  At  1000  feet  cut  off  motor  and  land 
within  200  feet  of  a  previously  designated  point. 

(4)  Land  over  an  assumed  obstacle  10  feet 
high  and  come  to  rest  within  1500  feet  from 
same. 

(5)  Cross-country  triangular  flight  of  30 
miles,  passing  over  two  previously  designated 
points.     Minimum  altitude  2500  feet. 

(6)  Straight-away  cross-country  flight  of  30 
miles.  Landing  to  be  made  at  designated  des- 
tination. Both  outward  and  return  flight  at 
minimum  altitude  of  2500  feet. 

(7)  Fly  for  45  minutes  at  an  altitude  of  4000 
feet. 

Any  candidate  who  successfully  passes  the 
Reserve  Military  Aviator  tests  will,  on  apphca- 
tion,  be  granted  the  "Expert  Aviator"  certifi- 
cate by  the  Aero  Club  of  America.  An  aviator 
desiring  this  certificate  must  apply  in  writing  to 
the  Secretary  of  the  Aero  Club  of  America,  297 
Madison  Avenue,  New  York  City,  sending  the 
report  of  his  R.M.A.  tests,  certified  by  the  com- 
manding officer  of  the  school,  by  one  of  the  of- 
ficers who  witnessed  the  tests,  or  by  one  of  the 
officers  of  the  administrative  staff,  together  with 
the  sum  of  $5. 

The  tests  for  the  R.M.A.  certificate  are  ac- 
cepted in  place  of  the  club's  own  tests  for  the 
Expert  Certificate.     These  are  as  follows : 

1.  A  cross-country  flight  from  a  designated 
starting  point  to  a  point  at  least  25  miles  distant, 
and  return  to  the  starting  point  without  alight- 
ing. 

2.  A  glide,  without  power,  from  a  height  of 
2500  feet,  coming  to  rest  within  164  feet  of  a 
previously  designated  point,  without  the  use  of 
brakes. 

3.  A  figure  8  around  two  marks  1640  feet 
apart.  In  making  turns  the  aviator  must  keep 
all  parts  of  his  apparatus  within  semicircles  of 
164  feet  radius  from  each  turning  mark  as  a  cen- 
ter. 


Enlisted  Aviators 


Observer 


Junior  Military  Aviator 


Aviation  Mechanicians. 


All  enlisted  men  except 
aviation  mechanics  and  en- 
listed aviators. 

The  uniform  insignia  of  the  U.  S.  Aviation  Service. 


Military    Aviator 


CHAPTER  XV 

REGULATIONS  FOR  UNIFORMS  OF  U.  S.  AERONAUTIC  PERSONNEL 

Regulations  and  Specifications  for  the  Uniform  of  Officer  Aviators  and  Enlisted  Men 
OF  the  Aviation  Section  of  the  Signal  Corps  Approved  June  22,  1917,  by  the 

Secretary  of  War 


Uniform  Specifications 

Body,  to  be  double  breasted,  loose  sack  coat 
of  soft  russet  leather,  standard-lined  through- 
out with  kersey;  to  be  easy  fitting  throughout, 
buttoned  down  the  side  with  five  large  horn  but- 
tons. 

Collar,  standing  and  falling;  standing,  to  be 
closed  in  front  with  hook  and  eye,  and  to  be 
about  one  inch  high ;  cloth  of  the  collar  to  be  of 
the  same  material  as  the  coat,  and  not  less  than 
four  inches,  or  more  than  five  inches  in  width, 
an  attachable  flap  of  the  same  material  as  the 
coat,  five  inches  in  length  and  two  inches  in 
width,  with  buttonhole  in  each  end  to  close  the 
front  of  the  collar  when  worn  closed. 

Pockets,  two  large  hip  pockets  covered  with 
a  flap,  slightly  rounded  at  the  corners,  the  open- 
ing to  be  horizontal  and  nine  inches  across ;  one 
large  breast  pocket  on  the  left  side  with  eight- 
inch  vertical  opening  at  the  center  line  of  the 
body,  the  pocket  to  slope  down  to  the  left.  All 
pockets  to  be  patch. 


190 


Skirt,  to  extend  one  third  of  the  distance  from 
the  point  of  the  hip  to  the  bend  of  the  knee,  ac- 
cording to  the  height  of  the  wearer. 

Shoulder  Looj^s,  on  each  shoulder  a  loop  of 
the  same  material  as  the  coat,  let  in  at  the  sleeve 
head-seam  and  reaching  to  the  edge  of  the  col- 
lar, buttoning  up  at  the  upper  end  with  a  small 
horn  button,  loops  to  be  about  two  inches  wide 
at  the  lower  end,  and  one  inch  wide  at  the  collai 
end,  and  cross-stitched  throughout  the  entire 
length. 

Sleeves,  to  have  flaps  with  buttons  to  tighten 
sleeve  around  the  wrist,  one  buttonhole  in  the 
flap,  with  two  buttons  on  the  sleeve  for  adjust- 
ing. 

Coats,  Aviator,  Anti-Sinking 

Body,  to  be  single-breasted,  sack  coat  of  ga- 
berdine with  the  anti-sinking  material  quilted 
between  the  outside  and  the  lining,  quality  and 
quantity  of  the  anti-sinking  material  to  be  of 
the  approved  standard,  to  button  down  the  front 
with  five  horn  buttons;  sleeves  not  to  be  quilted. 


I 


REGULATIONS  FOR  UNIFORMS  OF  U.  S.  AERONAUTIC  PERSONNEL    191 


Collar,  to  be  a  folding  collar  with  a  fold  not 
more  than  two  inches,  the  coat  to  fit  snugly 
around  the  neck. 

Pockets,  two  pockets,  patch,  one  on  each  hip. 
Six  inches  horizontal  opening  without  flaps. 

Skirts,  quilted  skirt  to  extend  one  third  of 
way  to  knee  from  the  hip,  according  to  the 
height  of  the  wearer. 

Shoulder  Loops,  on  each  shoulder  a  loop  of 
same  material  as  the  coat,  let  in  at  the  sleeve 
head-seam,  and  reaching  to  the  edge  of  the  col- 
lar, buttoning  at  the  upper  end  with  a  small  coat 
button ;  loops  to  be  about  two  inches  wide  at  the 
lower  end  and  one  inch  wide  at  the  collar  end, 
and  cross-stitched  throughout  the  entire  length. 

Face  Mask,  Aviators 

To  be  made  of  chamois  in  the  proper  shape  to 
conform  to  the  general  shape  of  the  head ;  skirts 
to  lay  flat  on  the  shoulder  and  chest,  and  to  be 
about  six  inches  long.  Eye,  nose,  and  mouth 
holes  to  be  cut  in  the  proper  place  for  each  in- 
dividual wearer. 

Flying  Suit 

To  be  made  of  gaberdine  of  approved  quality, 
unlined. 

Body,  a  one-piece  suit  with  opening  in  front 
from  crotch  to  neck;  fastened  together  with 
seven  horn  buttons. 

Collar,  a  falling  collar  with  one  and  one  half 
inch  fall,  fitting  snugly  around  the  neck. 

Shoulder  Loops,  on  each  shoulder  a  loop  of 
gaberdine  let  in  at  the  sleeve  head-seam,  and 
reaching  to  the  edge  of  the  collar,  buttoning  at 
the  upper  end  with  a  small  coat  button ;  loops  to 
be  about  two  inches  wide  at  the  lower  end,  and 
one  inch  wide  at  the  collar  end,  and  cross- 
stitched  throughout. 

Pockets,  to  have  two  breast  pockets,  one  on 
the  right  breast  to  have  an  eight-inch  horizontal 
opening  with  button  flap  the  height  of  armpit; 
the  one  on  the  left  side  to  have  a  vertical  open- 
ing nine  inches  in  length  without  flap,  but  with 
button  provided  for  closing;  pocket  to  be  large 
and  extend  in  a  downward  direction  toward  the 
left  hip. 


Sleeves,  sleeves  to  extend  well  down  on  the 
hand,  and  to  be  furnished  with  flaps  for  tighten- 
ing around  the  wrist,  flaps  to  be  of  the  same  ma- 
terial as  the  suit,  with  two  buttons  for  adjusting. 

Legs,  to  extend  down  to  the  ankles,  fitting 
rather  loosely,  with  a  flap  at  the  bottom  of  each 
leg  for  tightening  around  the  ankle;  two  but- 
tons for  adjusting  to  be  furnished. 

Buttons,  all  buttons  to  be  of  horn,  and  of  suit- 
able size  for  the  purposes  for  which  they  are  to 
be  used. 

Gloves,  Aviator,  Winter 

To  be  made  of  buckskin  or  pliable  russet 
leather  of  approved  quality,  lined  with  fleece  of 
unborn  lamb. 

Hand  of  glove  to  be  of  the  mitten  type,  with 
the  thumb  compartment  sufficiently  large  to 
permit  of  its  being  withdrawn  and  placed  with 
the  fingers.     There  shall  be  a  slit  across  the  in- 


Summer  flying  suit  of  moleskin  cloth,  unlined,  with  winter  cap  of 
soft  tan-colored  leather. 


192 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


terior  of  the  hand,  which  will  permit  the  fingers 
being  extended  in  the  opening,  the  slit  must  be 
sufficiently  overlapped  so  that  ordinarily  it  will 
remain  closed. 

Cuffs  to  be  of  the  gauntlet  type,  made  of  soft 
leather  and  extending  about  one  half  the  way 
up  to  the  elbow,  and  to  be  the  same  color  and 
material  as  the  glove  proper;  the  fur  in  the 
glove  to  extend  two  inches  up  the  gauntlet  from 
the  wrist  joint;  a  strap  to  be  furnished  for  tight- 
ening the  glove  around  the  wrist. 

Gloves,  Aviator,  Summer 

To  be  the  regular  gauntlet  type  of  soft  un- 
lined  buckskin  or  russet  leather,  with  soft  gaunt- 
let extending  about  one  half  the  way  to  the 
elbow. 

Goggles 

Transparent  part  to  be  made  of  triplex  glass ; 
mounting  for  the  glass  to  extend  well  away  from 
the  eyes;  the  part  of  the  goggles  nearest  to  the 
face  to  fit  snugly,  and  conform  to  the  general 
shape  of  the  face  in  order  to  keep  out  the  wind ; 
an  adjustable  elastic  tape  to  be  furnished  to 
hold  the  goggles  in  place. 

Amber  or  clear  glass  to  be  used,  according  to 
the  desire  of  those  wearing  them. 

Helmet,  Aviators,  Summer 

To  be  of  the  football  type,  of  brown  pliable 
sole  leather,  to  be  shaped  to  conform  to  the  head 
and  cover  the  entire  head  except  the  face.  Ear 
flaps  are  to  be  attached  for  the  protection  of  the 
ears,  and  by  having  shields  to  keep  out  the  wind. 
The  entire  helmet  is  to  be  lined  with  felt  one 
inch  thick,  and  to  be  fastened  under  the  chin 
with  an  elastic  tape  and  tie  string;  proper  holes 
for  ventilation  will  be  placed  over  the  entire  top 
of  the  helmet. 

Helmet,  Aviators,  Winter 

To  be  of  soft  russet  leather  lined  with  fur; 
to  he  shaped  so  as  to  cover  the  entire  head  ex- 
cept the  face;  to  be  fastened  under  the  chin  with 
a  .strap  and  buckle  or  patent  snap,  the  front  of 
the  helmet  to  extend  down  to  the  eyebrow. 


Aviation  Service 

Officers  of  the  Aviation  Service  who  are  Mil- 
itary Aviators  shall  wear  an  insignia  on  the  left 
breast,  the  insignia  to  be  embroidered  in  silver 
on  blue  background,  and  shall  be  two  wings  with 
the  shield  between;  the  wings  shall  be  three 
inches  from  tip  to  tip,  each  wing  shall  be  one 
and  one  eighth  inches  long,  and  nine  sixteenths 
inch  wide  at  the  contour  ends;  the  shield  shall 
be  nine  sixteenths  inch  high  and  five  eighths  inch 
wide,  with  the  letters  "U.  S."  one  quarter  inch 
high  in  the  center  below  the  horizontal  cross 
lines.     See  exhibit  A. 

Junior  Military  Aviators  shall  wear  on  their 
left  breast  the  same  insignia  described  for  the 
Military  Aviator,  except  that  the  right-hand 
wing  shall  be  omitted,  the  insignia  consisting  of 
one  wing  to  the  left  of  the  shield.  All  officers 
in  the  Aviation  service  shall  wear  the  Signal 
Corps  crossed  flags  on  their  collar.  See  Ex- 
hibit A. 


C'liiiiiKii^  skin  iiiii^k  iinil  Ic.'itlicr  coat 


REGULATIONS  FOR  UNIFORMS  OF  U.  S.  AERONAUTIC  PERSONNEL    198 


Mufflers 

Mujflers:  To  be  closely- woven  wool  or  cam- 
els' hair,  O.  D.  color,  sixteen  inches  wide  and 
one  and  one  half  yards  long,  the  ends  to  be  made 
up  with  a  fringe  the  same  as  those  in  common 
use. 

Shoes,  Aviator,  Winter 

To  be  of  soft  russet  leather,  lined  with  fleece, 
and  extending  one  half  way  to  knee;  to  have 
heavy  sole,  and  made  in  the  boot  form  or  to  be 
laced  up  wholly  or  partially  in  the  front. 

Boots,  Rubber,  Wading  (wading  pants) 

To  have  regular  boot  feet,  but  the  legs  to  ex- 
tend up  in  regular  trouser  form,  the  top  to  be  at 
a  height  just  under  the  armpits;  adjustable  sus- 
penders to  be  furnished  for  holding  the  tops  up. 

Breeches,  Winter,  Motorcycles 

To  be  made  of  gaberdine,  the  same  shape  and 
style  as  the  service  breeches  as  issued.  They 
will  be  lined  with  kersey  throughout. 

Face  Mash,  Goggles,  Helmet:  Same  as  for 
summer. 

Hood:  To  be  closely -woven  O.  D.  wool,  and 
cover  the  entire  head  except  face;  to  fit  snugly 
■and  extend  well  down  on  shoulders;  must  cover 
forehead  down  to  eyebrows. 

Insignia,  Sleeve 

Enlisted  men  of  the  Aviation  Section  shall 
have  a  navy  blue  cap  let  in  at  the  sleeve  head- 
seam  and  extending  down  the  sleeve  five  and  one 
half  inches  from  the  point  of  the  shoulder.  All 
men  as  hereinafter  specified  will  wear  the  in- 
signia as  described. 

A  four-bladed  propeller  with  center  three 
and  three  fourths  inches  from  point  of  shoulder, 
embroidered  in  white;  the  propellers  to  be  two 
inches  in  diameter,  two  of  the  blades  horizontal 
and  the  other  two  vertical;  three  fourths  of  an 
inch  above  the  top  tip  of  the  vertical  propeller 
l)lade  a  figure  showing  the  number  of  the  squad- 
ron to  which  the  man  belongs,  one  inch  high, 
and  embroidered  in  white.     See  Exhibit  C. 


Aviation  mechanician,  same  as  above  with  a 
white  embroidered  circle  added,  inside  of  circle 
to  be  one  and  one  fourths  inches  from  center  of 
the  propellers,  outside  of  the  circle  to  be  one  and 
three  eighths  inches  from  the  center  of  the  pro- 
pellers.    See  Exhibit  B. 

Enlisted  aviator,  on  the  same  blue  back- 
ground shall  be  embroidered  in  white,  the  in- 
signia as  hereafter  described.  A  pair  of  wings 
with  a  five-inch  spread  with  crossed  propellers 
between  them,  each  wing  to  be  one  and  seven 
eighths  inches  long  and  seven  eighths  of  an  inch 
high  at  the  inner  edge.  Propellers  to  be  one 
inch  across.  One  fourth  inch  above  the  top  tip 
of  the  vertical  propeller  shall  be  embroidered 
the  number  of  the  squadron  to  which  the  man 
belongs  in  figures  one  half  an  inch  high.  See 
Exhibit  C. 

Leg  gins:  All  mounted  men,  and  enlisted 
men  of  the  Aviation  Section,  Signal  Corps, 
canvas  with  leather  reenforcement,  as  issued. 

Muffler:     Same  as  for  aviators. 

Overalls,  Mechanics:  To  be  of  standard 
denim  material,  but  made  in  one  piece,  to  open 
up  in  front  from  crotch  to  neck,  and  button  up 
with  seven  small  buttons,  to  fit  snugly  around 
the  neck,  with  no  collar,  each  sleeve  to  be  pro- 
vided with  a  flap  for  tightening  around  the 
wrist;  to  have  two  hip  and  two  back  pockets, 
each  pocket  to  have  a  six-inch  opening,  the  legs 
to  extend  to  the  ankles,  and  to  be  provided  with 
flaps  for  tightening  around  the  ankles. 

Changes  In  Regulations  for  the  Uniforms  of 

the  United  States  Army,  1914, 

to  Cover  Aviation 

Special  articles  of  clothing  for  aviation  pur- 
poses are  provided  and  authorized  as  indicated 
hereafter.  They  are  in  addition  to  the  usual  ar- 
ticles of  clothing  for  garrison  and  field  service. 

All  officers  and  enlisted  men  on  duty  in  the 
Aviation  Section  will  obtain  them  on  memoran- 
dum receipt  from  the  Quartermaster.  They 
will  be  held  in  addition  to  all  the  other  clothing 
as  required  by  these  regulations. 

Breeches  for  Motorcycle  Messengers:  In 
cold  weather  motorcycle  messengers  in  the  Avi- 
ation Section  will  wear  kersey-lined  gaberdine 


194 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


breeches  of  standard  pattern  over  their  service 
breeches. 

Officers  detailed  in  the  Aviation  Section  and 
qualified  as  Mihtary  Aviators  will  wear  the 
double  or  if  quahfied  as  Junior  Military  Av- 
iator the  single  wing  shield  over  their  left 
breast. 

Officers  detailed  in  the  Aviation  Section  of 
the  Signal  Corps  will  wear  the  following  insig- 
nia to  show  their  qualifications : 

Military  Aviator:  A  silver-embroidered 
double  wing  shield  on  the  left  breast,  above  the 
line  prescribed  for  badges  and  medals. 

Junior  Military  Aviator:  A  single  wing  sil- 
ver-embroidered shield  on  the  left  breast,  above 
the  line  prescribed  for  badges  and  medals. 

Rubber  Wading  Boots  (wading  pants): 
For  use  of  officers  and  enlisted  men  on  duty  with 
Hydroaeroplane  Squadrons,  rubber  wading 
boots  with  the  top  extending  up,  in  the  form  of 
breeches,  well  beneath  the  armpits  will  be  fur- 
nished. They  will  be  held  up  by  adjustable 
suspenders. 

Coats,  Leather,  Aviator  (or  in  case  of  water 
squadron,  anti-sinking  coats)  :  Will  be  worn 
while  engaged  in  flying,  except  in  the  trop- 
ics, where  the  leather  coat  may  be  dispensed 
with. 

Face  Mask:  Of  chamois,  will  be  worn  by  of- 
ficers and  enlisted  men  flying  or  enlisted  men 
riding  motorcycles  in  cold  weather. 

Flying  Suit:  A  one-piece  flying  suit  of  gab- 
erdine used  by  all  officers  and  enlisted  men 
while  flying.  It  will  be  worn  under  the  leather 
coat. 

Winter:  They  will  be  worn  by  chauffeurs 
and  motorcycle  messengers  of  the  Aviation 
Section  of  the  Signal  Corps  during  cold 
weather. 

Aviator:  While  engaged  in  flying,  aviators 
will  wear  gloves  prescribed,  fur-lined  mittens 
with  gauntlet  tops  will  be  worn  in  cold  weather, 
and  the  plain  buckskin  or  leather  gauntlets  in 
warm  weather. 

Goggles:  Improved  type  of  triplex  goggles 
will  be  worn  by  all  aviators  and  motorcycle  mes- 
sengers in  the  Aviation  Section  of  the  Signal 
Corps  while  engaged  m  their  respective  duties. 
Chauffeurs  will  wear  them  in  the  winter.     Clear 


Brigadier-General  B.  D.  Foulois,  wearing  the  military  aviator 
insignia. 

or  amber  colored  glass,  according  to  the  desire 
of  the  person  using  them. 

Blue  denim  hat  will  be  worn  by  enlisted  men 
of  the  Coast  Artillery,  Quartermaster  Corps, 
Aviation  Section  of  the  Signal  Corps  and  Field 
Companies  of  the  Signal  Corps,  when  on  duty 
on  cable  ships,  with  the  fatigue  uniform. 

Helmets.  Aviators  and  Motorcycle  Messen- 
gers, will  wear  special  helmets  prescribed.  In 
the  summer  they  shall  be  of  pliable  russet 
leather,  lined  with  felt ;  in  the  cold  weather,  avia- 
tors will  wear  a  fur-lined  soft  russet  leather 
helmet. 

On  the  shoulder  loops  of  the  ser\'ice  and  white 
uniforms,  and  aviators'  outside  suits  or  coats, 
metal  insignia  of  rank  will  be  worn  as  fol- 
lows: 

Enlisted  men  of  the  Aviation  Service  will 
wear  embroidered  insignia  on  the  right  sleeve 
just  below  the  shoulder  as  follows: 

Enlisted  men  in  the  Aviation  Section  will 
wear  a  white  embroidered  insignia  with  crossed 
propellers,  with  the  number  of  their  squadron 


REGULATIONS  FOR  UNIFORMS  OF  U.  S.  AERONAUTIC  PERSONNEL     195 


above,  on  blue  background,  on  the  upper,  right 
sleeve. 

Aviation  mechanicians  will  have  in  addition, 
a  white,  embroidered,  circle  around  the  propel- 
lers. 

Enlisted  aviators  will  wear  an  insignia  with 
double  wing,  crossed  propellers  with  the  numer- 
ical designation  of  the  squadron  embroidered 
on  the  blue  background  on  the  upper  right 
sleeve. 

Mufflers:  Aviators,  motorcycle  messengers 
and  chauffeurs  of  the  Aviation  Section  will 
wear  an  O.  D.,  closely-woven  wool  muffler  dur- 
ing cold  weather. 

While  doing  fatigue,  enlisted  men  of  the  Avi- 
ation Section  will  wear  a  one  piece  denim  me- 
chanic's overalls,  as  authorized. 

Officers,  Aviation:  A  soft  russet  leather 
fleece-lined,  high-top  shoe  with  heavy  sole  will 
be  worn  by  officer  aviators  while  flying  during 
cold  weather. 

Enlisted  men  aviators,  and  motorcycle 
messengers  will  wear  high-top  russet  leather, 
heavy-soled  shoes,  lined  with  fleece,  dur- 
ing cold  weather,  while  flying  or  riding  motor- 
cycles. 

Aviators  and  Motorcycle  Messengers  will 
wear  special,  closely-knit,  all-wool,  coat  sweater 
during  cold  weather. 

Aviation  Officers:  In  addition  to  the  articles 
listed  under  "a"  and  "b"  for  mounted  and  dis- 
mounted officers,  officers  acting  as  pilot  will  se- 
cure and  have  in  their  possession  the  following 
articles : 


I 


1.  Aviator's  winter  helmet. 

2.  Aviator's  summer  helmet. 

3.  Clear  or  amber,  triplex  glass  goggles. 

4.  Muffler. 

5.  One-piece  flying  suit. 

6.  Leather  coat. 

7.  Aviator's  winter  gloves. 

8.  Aviator's  summer  gloves. 

9.  Aviator's  winter  shoes. 

10.  Aviator's  sweater. 

11.  Aviator's  face  mask. 


Note:  In  case  of  the  officer  being  with  a 
water  squadron,  an  anti-sinking  coat  will  be  sub- 
stituted for  the  leather  coat. 


UNIFORMS  OF  THE  UNITED  STATES 
ARMY 

Table  of  Occasions 

Officers 

Service  Uniform  and  Equipment 


Occasions              By  whom 

Articles 
E. 

In 

minter. 

1. 

Aviator's   winter 

helmet. 

2. 

Face   mask. 

3. 

Goggles. 

4. 

Muffler. 

S. 

Flying  suit. 

6. 

Aviator's    winter 

gloves. 

7. 

Aviator's   shoes. 

8. 

Sweater. 

9. 

O.  D.   Shirt. 

1.     For  all  offi- 

10. 

Service  breeches. 

cer   aviators 

U. 

Leather  Coat. 

,      ,-,                 .           and   observ- 
4.     For      garri-                       ^^^ 

E. 

^°°     ''"ty          engaged     in 

In 

summer. 

flying     land 

1. 

Aviator's     summer     hel- 

machines. 

met. 

2. 

Goggles. 

3. 

One-piece  flying 

suit. 

4. 

Leather  coat. 

5. 

Aviator's  summer 

gloves. 

6. 

O.  D.  Shirt. 

7. 

Service  breeches. 

8. 

Russet   leather   shoes. 

9. 

Russet  leather  leggins. 

In 

tropics. 

Same   as   summer 

except 

omit  leather  coat. 

Note  1.  For  water  machines  substitute  in  winter  anti-sinking 
coat  for  leather  coat.  In  summer,  substitute  anti- 
sinking  coat  for  leather  coat.  In  tropics,  substitute 
anti-sinking  coat  for  flying  suit  and  leather  coat. 

E. 
Add     to     garrison     uniform. 

On  person 

1.  Identification   tag. 

2.  First      aid      packet      and 

pouch. 
For    all    officer   3.     Watch, 
aviators       a  n  d   4.     Notebook  and  pencil. 
5.     For       field   observers    while   5.     Compass. 
duty  engaged  in   fly- 

inff.  In  machine 

1.  Haversack  containing 

meat     can,     knife     and 
fork,  and  spoon. 

2.  Canteen  with  cover. 

3.  Cup. 

4.  Field  Glasses  for  Observ- 

ers only. 

Note: — When  not  flying,  aviators  and  observers  will  substitute 
campaign  hat  for  aviator's  head  gear. 


helmet. 


la. 


Enlisted  Men 

Winter 

1. 

Aviator's   winter 

2. 

Face  mask. 

3. 

Goggles. 

For    garri- 

All enlisted  avi-     4. 

Muffler. 

son    duty 

ators     and     ob-     5. 

Flying  suit. 

while      en- 

servers.                     6. 

Aviator's    winter 

gaged   in 

T. 

Aviator's  shoes. 

flying- 

8. 

Sweater. 

9. 

O.   D.   Shirt. 

10. 

Service  breeches. 

11. 

Leather  coat. 

gloves. 


196 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Occasion* 


By  whom. 


Articles 

Summer. 

I.  Aviator's  summer  helmet. 

J.  Goggles. 

3.  One-piece   flying  suit. 

4.  Leather  coat. 

5.  Aviator's  summer  gloves. 

6.  O.  D.  Shirt. 

7.  Service  breeches. 

8.  Russet   leather   shoes. 

9.  Russet  leather  leggins. 

In  tropics. 

Same  as  summer. 
Omit  leather  coat. 


Ic. 


Ic. 


For   men   tend- 
ing. 


t'oT   garri- 
son    duty,   For  Chauffeurs. 
.\  VI all  on 
Section. 


Winter. 


For    garri- 
son  duty.  For  mechanl- 
Aviation   cians. 
Section. 


Winter  cap. 
Alasl«an  Pea  Jacket. 
One      piece       mechanic's 

suit. 
O.  D.  Shirt. 
Service  breeches. 
Russet  Shoes. 
Arctics. 
Gloves,  woolen. 


1. 
2. 
3. 

4. 
S. 
6. 

7. 
8. 

Summer. 

1.  Blue  Denim  hat. 

2.  One      piece      suit,      me- 
chanics. 

3.  O.  D.  Shirt. 

4.  Service  breeches. 

5.  Russet  shoes. 

Tropics. 

Same  as  summer. 

Omit  shirt  and  breeches. 

Water  Machines. 

Add    wading   pants,    and 
omit  one  piece  suit. 

Winter 

1.  Winter  cap. 

2.  Goggles. 

3.  Muffler. 

4.  Alaskan    Pea   Jacket. 

5.  Aviator's    winter    gloves. 

6.  O.  D.  Shirt. 

7.  One      piece      mechanic's 

suit. 

8.  Service  breeches. 

9.  Leggins,  leather. 
10.     Russet  shoes. 


Oceation 


lb. 


For  garri- 
son duty. 
Aviation 
Section. 


By  who 

m. 

A rticles 

Summer. 

1. 

Service  cap. 

2. 

One  piece  mechanic's 
suit. 

3. 

O.  D.  Shirt. 

4. 

Service  breeches. 

S. 

Leather  leggins. 

6. 

Russet  shoes. 

Tropics. 

Same  as  summer,  except. 

omit    O.    D.    Shirt,    and 

service  breeches. 

Winter. 

1. 

Aviator's   winter   helmet. 

2. 

Hood. 

3. 

Goggles. 

4. 

Face  Masks. 

S. 

Muffler. 

6. 

Alaskan  Pea  Jacket. 

7. 

Fleece-lined    gauntlets. 

8. 

Kersey-lined  breeches. 

9. 

Aviator's  winter  shoes. 

10. 

O.  D.  Shirt. 

11. 

Service  breeches. 

12. 

Leather  leggins. 

For    all 

motor- 

Summer. 

cycle 

messen- 

1. 

Aviator's     summer     hel- 

gers. 

met. 

2. 

Goggles. 

3. 

One  piece  mechanic's 
suit. 

4. 

Gloves,  summer,  aviators. 

5. 

Leather  leggins. 

6. 

O.  D.  Shirt. 

7. 

Service  breeches. 

8. 

Russet  shoes. 

6a. 


For  Field 
Service  for 
Aviation 


Tropical. 

Same  as  summer,  except 
omit  gloves,  O.  D.  Shirt, 
and  service  breeches. 

For       enlisted 
aviators. 
For    motorcycle 

men.  ^dd  to   garrison  uniform. 

For     mechani-   1.    Identification  tag. 
cians. 

For    Chauf- 
feurs. 


J 


CHAPTER  XVI 


AERONAUTIC  MAPS 


Maps  have  always  been  most  important  fac- 
tors in  military  and  naval  operations,  as  they 
have  been  important  factors  in  peaceful  travel 
over  land  and  water. 

A  map  is  as  important  to  the  aviator  as  it  is 
to  the  navigator  at  sea.  As  the  mariner's  chart 
must  tell  the  navigator  of  currents,  depths  of 
water,  and  location  of  rocks  and  reefs,  so  the 
aeronautic  map  must  tell  the  aviator  the  char- 
acter of  the  land  and  the  configuration  of  the 
bodies  of  water  below  him.  It  must  show  the 
land  as  it  is,  the  exact  shape  of  cities,  woods,  and 
lakes;  the  trend  of  rivers,  railroads,  and  roads; 
it  must  indicate  clearly  the  prominent  land- 
marks and  the  established  aerodromes  and  open 
fields  suitable  for  landings,  etc.,  etc.  In  other 
words,  the  aeronautic  map  must  show  the  con- 
tours and  configuration  of  the  land  as  closely  as 
possible  to  the  way  it  looks  to  the  aviator  from 
the  air. 

Five  Types  of  Aeronautic  Maps 

There  are  four  types  of  aeronautic  maps  used 
in  the  present  war,  and  one  type  is  in  prepara- 
tion in  the  United  States.  The  former  are  as 
follows : 

(1)  The  General  Aeronautic  Map. — This  is 
based  on  existing  maps,  usually  on  a  scale  of 
1 :200,000,  but  differs  from  the  average  maps  in 
that  the  roads  are  shown  in  red,  the  railroads 
in  black,  forests  and  woods  in  green,  and  water- 
ways in  blue. 

(2)  The  Special  Aeronautic  Map. —  (Illus- 
trated herewith.)  Besides  including  every- 
thing in  the  first  chart,  this  shows  aerodromes 
for  aeroplanes  and  dirigibles,  landing  fields 
where  there  are  no  hangars,  stations  where  gas 
for  dirigibles  is  obtainable,  the  approximate 
shape  of  cities,  towns,  and  villages,  and  such 
landmarks  as  prominent  churches,  railroad  sta- 


tions, windmills,  smokestacks,  castles,  and  mon- 
uments. 

These  maps  are  used  in  long-distance  flights 
and  raids.  When  a  flight  is  planned  the  avia- 
tors go  over  the  map,  lay  down  the  route  to  be 
followed,  and  study  the  details  given  on  the 
map,  together  with  any  other  information  they 
may  be  able  to  obtain  regarding  the  configura- 
tion of  the  land  over  which  they  will  fly,  possible 
landing  places,  etc.  It  is  needless  to  add  that 
the  aviators  make  every  effort  to  ascertain  as 
nearly  as  possible  the  nature  of  the  enemy  coun- 
try, in  order  to  recognize  the  locations  where 
bombs  are  to  be  dropped,  as  well  as  where  anti- 
aircraft guns  are  most  apt  to  be  waiting. 

(3)  The  Special  Aeronautic  Map  for  Per- 
manent Aerial  Routes. — This  gives  only  im- 
portant information  required  by  the  aviator  to 
travel  over  a  certain  route.  This  type  of  map, 
which  is  illustrated  herewith,  originated  in  Italy, 
and  has  not  yet  been  put  into  general  use  out- 
side of  Italy.  It  is  a  most  remarkable  map. 
The  rivers  and  lakes  are  shown  in  blue,  in  their 
exact  form.  The  roads  are  given  in  brown,  the 
railroads  in  black.  The  ajiproximate  shape  of 
cities  and  towns  is  given  in  black,  and  the  most 
prominent  building  of  each  city  or  town,  to  be 
used  as  a  landmark,  is  reproduced.  The  woods 
and  forests  are  also  shown;  and  the  elevation  at 
different  points  is  given  in  meters,  so  that  the 
pilot  can  rise  in  case  he  is  caught  in  a  fog  after 
passing  a  given  place,  and  thus  avoid  flying  into 
a  hill.  In  view  of  the  fact  that  his  altimeter  or 
barograph  gives  only  the  altitude  above  sea- 
level,  or  the  altitude  from  the  point  of  start, 
it  is  necessary  for  the  aviator  to  know  the  ap- 
proximate elevation  of  the  land  below. 

The  aerial  route  to  be  followed,  which  is 
permanent,  is  marked  in  red  dotted  lines.  The 
aerodromes  are  shown  in  red  circles;  the  land- 
ing-places which  permit  landing  from  two  points 


197 


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are  indicated  by  two  red  dots  of  the  same  size, 
connected  with  a  red  line;  the  landing-places 
which  permit  landing  only  from  one  side  are 
indicated  by  one  red  dot,  connected  by  a  short 
line  and  a  smaller  red  dot.  These  dots  are  most 
important,  as  the  large  dot  represents  the  ap- 
proximate place  where  the  wheel  of  the  aero- 
plane must  touch  on  landing.  The  line  that 
connects  it  with  the  smaller  dot  shows  the  direc- 
tion toward  which  the  aeroplane  must  run  in 
landing.  The  distance  between  the  first  dot 
and  the  second  is  usually  about  300  meters,  and 
the  width  is  usually  about  100  meters.  This 
type  of  map  greatly  facilitates  aerial  navigation. 
(4)  The  Photographic  Map  of  Sectors. — 
Military  operations  are  based  on  these  maps. 


This  style  of  map  is  most  important,  and  is  cor- 
rected daily,  often  several  times  a  day,  to  include 
the  changes  shown  by  photographs  taken  by 
aviators  from  their  aeroplanes.  These  photo- 
graphic maps  show  the  configuration  to  the  most 
minute  detail  and  with  the  utmost  care,  as  the 
success  of  certain  operations  depends  upon  the 
exactness  of  the  smallest  topographical  detail. 

Aerial  photography  is  now  almost  an  exact 
science.  An  aviator  at  a  height  of  from  6000 
to  8000  feet  can  take  a  photograph  which  will 
include  and  show  clearly  all  of  Manhattan  Is- 
land; and  the  photograph  can  be  enlarged  to 
show  the  main  streets,  docks,  bridges,  and,  of 
course,  the  buildings.  A  series  of  photographs 
could  be  taken  from  New  York  to  Albany  which 


would  permit  making  photographic  maps  of  the 
entire  route,  and  show  every  detail  on  an  exact 
scale.  This  could  not  be  accomplished,  even 
with  the  expenditure  of  years  of  time  and  large 
sums  of  money,  by  any  other  method.  The 
expert  maker  of  photographic  maps  quickly  fig- 
ures out  the  scale,  and  combines  photographs  to 
make  a  continuous  map. 

An  aviator  might  fly  from  Albany  to  New 
York  in  what  is  considered  a  slow  aeroplane  at 
about  70  miles  an  hour,  and  take  a  motion-pic- 
ture of  the  entire  route,  giving  the  exact  topo- 
graphical conditions,  thus  permitting  the  mili- 
tary authorities  within  twenty-four  hours  to 
conduct  operations  with  absolute  certainty  as  to 
conditions  obtaining  throughout  this  region. 

(5)   The    Sj^erry    Aeronautic    Map. — This 


type  of  map  is  made  on  the  basic  principle  of  the 
"Special  Aeronautic  Map  for  Permanent  Air 
Routes"  described  above,  although  it  was 
evolved  entirely  independently  of  the  latter,  and 
has  several  improvements. 

Mr.  Lawrence  B.  Sperry  has  been  working 
on  these  maps  and  with  the  cooperation  of  the 
Committee  on  Aeronautic  Maps  and  Landing 
Places  of  the  Aero  Club  of  America,  the  Aerial 
League  of  America,  and  the  Aeronautic  Li- 
brary is  preparing  a  map  of  the  Wilson  Airway 
from  New  York  to  San  Francisco,  which  will 
make  it  possible  for  an  aviator  to  fly  across  the 
continent  without  the  possibility  of  losing  his 
way. 

Maps  of  the  air-routes  between  New  York 
and  Chicago,  New  York  and  Newport  News, 


200 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Va.,  and  about  Long  Island,  have  also  been  pre- 
pared and  are  ready  for  the  insertion  of  the 
aerodromes  now  being  established  by  the  Army 
Air  Service  and  civil  organizations,  and  of 
other  landmarks. 

The  plan  is  to  also  show  on  the  map  the  land- 
ing-places for  twenty-five  or  fifty  miles  on  either 
side  of  the  straight  route,  and  eventually  to 
give  sketches  of  the  shape  of  cities  and  towns, 
or  the  more  prominent  landmarks  which  strike 
the  eye  of  the  air-traveler. 

The  map  being  prepared  of  the  Wilson  Aerial 
Highway  will  cover  a  straight  route  from 
New  York  to  San  Francisco,  but  there  will  be 
lines  leading  from  the  main  line  to  central  land- 
ing-places, such  as  Erie,  Cleveland,  and  Detroit. 
All  the  headings  are  magnetic  on  these  maps, 
and  the  arrows  indicate  headings  in  either  di- 
rection. 

The  true  heading  from  one  city  to  another  is 
determined  by  projecting  the  line  of  flight  be- 
tween these  two  cities,  and  then  transferring 
this  line,  by  means  of  parallel  rulers,  to  the 
nearest  compass  rose,  from  which  the  true  head- 
ing is  obtained.  As  the  difference  between  the 
geographical  and  magnetic  North  Pole  differs 
at  various  places  on  the  earth's  surface,  it  is 
necessary  to  correct  frequently  for  this  differ- 
ence, which  is  known  as  "variation."  In  the 
vicinity  of  Chicago  the  magnetic  needle  is  found 
to  point  to  true  geographical  north,  but  as  the 
journey  is  continued  eastwardly,  the  error  will 
be  noticed  to  increase  to  almost  10  degrees  west 
at  New  York.  As  all  the  headings  on  this  chart 
have  been  laid  out  "magnetic,"  or  with  variation 
taken  into  consideration,  the  pilot  simply  steers 
his  craft  on  the  charted  headings.  Wherever 
the  variation  is  east,  it  is  necessary  to  subtract 
from  the  true  heading,  and  when  it  is  west,  one 
must  add  the  necessary  number  of  degrees,  in 
order  to  obtain  the  proper  indication. 

As  soon  as  regular  air-lines  are  established 
to  carry  passengers  and  mail,  and  aircraft  start 
from  a  given  station  at  a  given  time  daily,  there 
will  be  added  to  this  map  the  approximate  time 
at  which  aircraft  will  pass  certain  places,  so  that 
the  aviator  can  navigate  the  air  with  even  less 
trouble  than  the  sailor  navigates  the  sea.  In 
fact,  an  aeroplane  equipped  with  the  Sperry 


automatic  pilot  could  be  set  to  follow  the  com- 
pass direction  in  trips  of  a  few  hundred  miles, 
and  thereafter  the  pilot  would  have  practically 
nothing  to  do,  as  the  automatic  pilot  would  con- 
trol his  machine  completely.  The  pilot  would 
only  have  to  guard  against  the  drift  due  to  side- 
winds, which  he  would  do  by  occasionally  glanc- 
ing at  his  map  and  looking  below  to  see  whether 
the  prominent  landmarks  checked  with  the  land- 
marks shown  on  his  map.  Knowing  the  speed 
of  his  machine,  and  having  the  approximate  time 
required  to  reach  different  places,  a  glance  at 
the  watch  would  tell  him  at  what  point  he  should 
be  at  that  hour,  when  he  could  ascertain  whether 
the  landmarks  below  were  similar  to  those  shown 
on  the  map. 

The  Map  with  Photographic  Reproduction 

of  Route  and  Information  Regarding 

Prevailing  Winds 

As  soon  as  large  aeroplanes  with  a  broad 
dash-board  are  used,  it  will  be  possible  to  make 
maps  larger,  and  to  include  on  the  ipiargins  a 
film  reproduction  of  the  entire  route,  or  merely 
important  places.  It  may  also  be  found  advis- 
able to  print  on  the  margin  information  regard- 
ing prevailing  winds  to  be  met  at  different 
altitudes. 

It  may  later  be  found  that  films  can  easily 
be  taken  of  the  entire  route  from  New  York  to 
San  Francisco,  and  between  other  control 
points.  Such  a  film  can  be  enlarged  to  have  a 
width  of  between  9  and  12  inches,  and  the  water 
can  be  painted  blue,  the  forests  and  woods 
green,  the  roads  brown,  the  railroads  black,  the 
aerodromes  red,  etc.  This  will  furnish  an  exact 
map,  not  only  for  the  aviator,  but  for  other 
commercial  and  scientific  purposes,  such  as  de- 
veloping railroads  and  highways,  and  surveying 
for  various  purposes. 

It  is  quite  possible  that  the  entire  cost  of 
making  a  photograj)hic  aeronautic  map  of  the 
route  between  New  York  and  San  Francisco 
will  not  be  found  as  high  as  that  of  surveying  a 
few  miles  to  make  an  average  topographic  map. 

The  War  Prevented  an  International  Con- 
vention on  Aeronautic  Cartography 

The  war  prevented  the  assembling  of  an  in- 
ternational convention,  held  under  the  auspices 


AERONAUTIC  MAPS 


201 


of  the  Aero  Club  of  America,  to  discuss 
and  decide  on  the  basic  principles  for  an 
aeronautic  map  of  the  world  to  be 
adopted  by  all  nations.  This  convention 
was  being  ai'ranged  in  the  United  States 
by  the  Aero  Club  at  the  suggestion  of 
Rear- Admiral  Robert  E.  Peary,  Chair- 
man of  the  Committee  on  Aeronautic 
Maps  and  Landing-Places  of  the  Aero 
Club  of  America.  Admiral  Peary  at- 
tended the  Tenth  International  Geo- 
graphical Congress,  held  at  Rome  in 
January,  1913,  at  which  the  subject  of 
aeronautic  maps  was  discussed.  The 
report  of  this  congress  and  the  principal 
address  delivered  were  translated  from 
Italian  by  the  writer  and  printed  in 
"Flying,"  the  organ  of  the  Aero  Club  of 
America,  for  September  and  October, 
1913. 

At  this  conference  no  decision  was 
reached,  or  action  taken,  toward  adopt- 
ing basic  principles  for  the  making  of 
aeronautic  maps,  because  it  was  agreed  by  the 
delegates,  as  it  had  been  agreed  by  the  delegates 
that  attended  the  congress  of  the  International 
Aeronautic  Federation  at  Vienna  in  June,  1912, 
that  the  first  step  to  be  taken  should  be  to  agree 
on  a  scale  and  conventional  signs  to  be  adopted 
for  an  aeronautic  map  of  the  world.  The  aero- 
nautic map  of  the  world  was  then  to  be  supple- 
mented by  aeronautic  maps  of  different  coun- 
tries, and  of  parts  of  different  countries,  to  be 
made  on  the  accepted  scale  with  the  use  of  the 
same  conventional  signs. 

It  was  to  bring  about  this  international  agree- 
ment that  the  Aero  Club  of  America  was  ar- 
ranging to  hold  an  international  convention  in 
the  United  States,  the  object  being  to  do  for 
the  world  aeronautic  map  what  was  done  for  the 
world  chart,  as  proposed  by  the  International 
Geographical  Congress  at  Geneva  in  1908. 
The  purpose  of  this  congress  was  not  only  to 
agree  on  a  scale  and  conventional  signs  to  be 
adopted  for  the  world  aeronautic  map,  but  also 
to  make  the  necessary  arrangements,  through 
diplomatic  channels  or  otherwise,  to  facilitate 
the  execution  of  those  sheets  of  this  map  which 
overlapped  the  frontiers  of  different  countries. 


A  Sperry  map-holder  and  map. 

The  war  prevented  the  holding  of  this  con- 
vention, but  the  committee  on  aeronautic  maps 
and  landing-places  of  the  Aero  Club  of  America 
continued  its  work  to  advance  this  project. 
The  members  of  this  committee  are  as  follows: 
Rear  Admiral  Robert  E.  Peary,  Chairman; 
Henry  Woodhouse,  Vice-Chairman;  Bion  J. 
Arnold,  Vincent  Astor,  A.  G.  Batchelder, 
George  F.  Baker,  Jr.,  Captain  Robert  A.  Bart- 
lett,  Bernard  H.  Baruch,  August  Belmont, 
James  Gordon  Bennett,  Cortlandt  F.  Bishop, 
Captain  Mark  L.  Bristol,  U.  S.  N.;  Starling 
Burgess,  Godfrey  L.  Cabot,  President  Aero 
Club  of  Xew  England;  President  Manuel  Es- 
trada Cabrera  of  Guatemala;  ISIajor  Joseph  E. 
Carberry,  U.  S.  A.;  Major  C.  C.  Culver,  U.  S. 
A.;  Newcomb  Carlton;  Lieut.  Col.  Charles  De 
F.  Chandler,  U.  S.  A.;  Captain  W.  I.  Cham- 
bers, U.  S.  'N.;  J.  Parke  Canning,  Roy  D. 
Chapin,  Alexander  Smith  Cochran,  Robert  J. 
Collier,  Howard  E.  Coffin,  Chairman  Aircraft 
Production  Board;  Roy  U.  Conger,  Glenn  H. 
Curtiss,  Commander  Cleveland  Davis,  U.  S.  N.; 
Lieut.  F.  Trubee  Davison,  N.  R.  F.  C;  Lieut. 
Col.  E.  A.  Deeds,  S.  O.  R.  C;  Charles  de  San 
Marsano,  Charles  Dickinson,  President  Aero 


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MIHt&ICItO   MLLA  OUCAftA 


SpecUI  aeronautic  map  of  permanent  aerial  routes. 


Club  of  Illinois;  F.  G.  Diffin,  W.  Earl  Dodge, 
Brig.  General  Robert  K.  Evans,  U.  S.  A. ;  Rear 
Admiral  Bradley  A.  Fiske,  U.  S.  N.;  Elbert 
H.  Gary,  John  Hays  Hammond,  Jr.;  W.  Av- 
erill  Harriman,  Alan  R.  Hawley,  William 
Hawley,  Henry  B.  Joy,  Frank  S.  Lahm,  Cap- 
tain A.  B.  Lambert,  A.  S.  R.  C;  Henry  Lock- 
hart,  Jr.;  Lieut.  Robert  A.  Lovett,  R.  N.  F.  C; 
Harold  F.  MeCormick,  Captain  J.  C.  McCoy, 
Emerson  McMillan,  Eugene  Meyers,  Jr. ;  Cap- 
tain James  E.  Miller,  S.  O.  R.  C;  Lieut.  Com- 
mander Henry  C.  Mustin,  U.  S.  N.;  George 
M.  Myers,  President  Aero  Club  of  Kansas 
City;  J.  D.  Park,  George  W.  Perkins,  Prof. 
Charles  L.  Poor,  Augustus  Post,  Ralph  Pulit- 
zer, Col.  Samuel  Reber,  U.  S.  A.;  Ogden  Mills 
Reid,  Thomas  F.  Ryan,  Alberto  Santos  Du- 
mont,  Frank  A.  Seiberling,  Hon.  William  G. 
Sharp,  Edwin  C.  Shaw,  I^awrence  B.  Sperry, 
Brig.  General  George  O.  Squier,  Chief  Signal 
Officer,  U.  S.  A.;  James  S.  Stephens;  Lieut. 
Commander  J.  H.  Towers,  U.  S.  N.;  K.  M. 
Turner,  George  W.  Turney,  Col.  Cornelius 
Vanderbilt,  W.  K.  Vanderbilt,  L.  A.  Vilas, 
Rodman  Wanamaker,  Monroe  Wheeler,  Schuy- 
ler Skaats  Wheeler,  Harry  Payne  Whitney,  G. 
Douglas  Wardrop,  Hugh  L.  Willoughby, 
Henry  A.  Wise  Wood,  Orville  Wright,  Wil- 
liam Wallace  Young,  A.  Francis  Zahm. 

Existing  Aeronautic  Maps  Are  the  Result  of 
Work  by  Aero  Clubs 

The  existing  aeronautic  majjs  are  the  result 
of  work  done  by  the  Aero  Clubs  of  France, 
Italy,  and  United  States.  The  same  pioneer 
sportsmen  and  volunteers  who  were  responsible 
for  developing  aeronautics  in  the  different  coun- 
tries up  to  the  time  of  the  war,  were  also  respon- 
sible for  the  first  aeronautic  maps. 

The  writer  well  remembers  how  these  pio- 
neers, now  considered  as  "pioneers  and  authori- 
ties in  aeronautics"  and  given  credit  for  having 
had  "wonderful  foresight"  at  that  time,  were 
considered  visionaries  in  1910,  as  even  in  1914f. 
Few  people  were  willing  to  admit  that  aircraft 
would  develop  within  fifty  or  one  hundred  years 
to  such  a  point  that  aeronautic  maps  would  be 
needed  for  aerial  navigation.  These  pioneers 
nevertheless  went  on  with  their  work. 


AERONAUTIC  MAPS 


208 


In  1910  officials  of  the  Automobile  Club  of 
America  and  the  Aero  Club  of  America  com- 
bined their  efforts  to  make  a  topographical  map 
of  Western  Long  Island  for  aeronautic  pur- 
poses. 

The  Aero  Club  of  France  started,  in  1911,  to 
make  an  aeronautic  map  of  France.  This  aero- 
nautic map  was  to  consist  of  about  100  sheets, 
24  of  which  have  already  been  issued  and  are 
used  extensively  by  the  French  and  British  Fly- 
ing Corps.  Mr.  Charles  Lallemand,  the  well- 
known  French  scientist,  is  the  chairman  of  the 
aeronautic  maps  committee  of  the  Aero  Club 
of  France.  The  basic  principle  on  which  aero- 
nautic maps  are  now  being  made  by  the  Aero 
Club  of  France  has  been  revised  so  as  to  bring 
them  up  to  date  and  meet  military  needs. 

In  Italy  the  work  of  making  aeronautic  maps 
has  been  shared  between  the  aeronautic  authori- 


ties, the  authorities  of  the  Touring  Club  of 
Italy,  and  the  members  of  the  National  Com- 
mission of  Aerial  Touring.  The  Italian  pio- 
neers in  aeronautic  toj)ography  include  Senator 
G.  Celoria,  the  chairman  of  the  National  Com- 
mission on  Aerial  Touring;  Commander  Gio- 
vanni Roncagli,  Royal  Italian  Navy  and  secre- 
tary general  of  the  Tenth  International  Geo- 
graphical Congress;  Mr.  C.  Usuelli,  and  other 
well-known  Italian  scientists.  The  pioneer 
work  of  these  organizations  has  been  of  great 
value  to  the  military  authorities  of  their  re- 
spective countries  during  the  present  war.  In 
France  and  Italy  the  Aero  Clubs  were  practi- 
cally the  only  sources  from  which  the  necessary 
information  covering  aeronautic  maps  could  be 
obtained,  as  no  attention  had  been  paid  to  this 
subject  before  the  war  by  the  military  authori- 
ties. 


CHAPTER  XVII 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


As  related  in  the  chapter  on  "The  Evolution 
of  the  ^lilitary  Aeroplane,"  the  United  States 
Army  holds  the  distinction  of  being  the  first 
army  in  the  world  to  acquire  an  aeroplane. 

The  order  for  the  first  Wright  machine  was 
placed  early  in  1908,  and  tests  were  made  at 
Fort  Myer,  Va.,  in  September  of  that  year. 
These  resulted  in  an  accident  on  September  17, 
in  which  Orville  Wright,  the  pilot,  was  severely 


which  officers  of  line  organizations  could  serve 
on  special  details.  Lieut.  Foulois  was  sent  to 
San  Antonio  to  teach  himself  to  fly  with  the 
Wright  machine. 

Owing  to  the  failure  of  Congress  to  allow  an 
appropriation  for  army  aeronautics,  the  work  of 
developing  this  branch  of  the  service  practically 
ceased  in  1910-11,  and  officers  attached  to  the 
Aeronautic    Division    kept    up    their    practice 


injured,  and  Lieutenant  E.  Self  ridge,  the  pass-     mainlv  by  attending  aviation  meets  and  follow- 


enger,  was  killed.  The  next  tests  took  place  at 
Fort  Myer  in  July,  1909.  This  machine  was 
accepted  by  the  Government,  and  Lieutenants 
Frank  Purdy  Lahm  and  Benjamin  D.  Foulois 
were  assigned  to  receive  instruction  from  the 
Wrights. 

An  aviation  camp  was  established  at  College 
Park,  Md.,  and  Captain  Charles  DeF.  Chand- 
ler, then  disbursing  officer  of  the  Signal  Corps, 
was  appointed  Officer  in  Charge  of  the  Aero- 
nautic Division.  The  following  officers  were 
taught  to  pilot  the  Wright  machine  by  Wilbur 
Wright  during  October  and  November,  1909: 
Captain  Charles  DeF.  Chandler,  Lieutenant  F. 
P.  Lahm,  Lieutenant  Benjamin  D.  Foulois, 
Lieutenant  Frederick  E.  Humphreys,  Lieuten- 
ant T.  deWitt  Milling,  Lieutenant  H.  H.  Ai-- 
nold,  and  Lieutenant  George  C.  Sweet,  the  last 
being  assigned  by  the  Navy  Department. 

The  first  dirigible,  delivered  to  the  United 
States  Army  by  Captain  Thomas  G.  Baldwin, 
was  first  flown  at  Fort  Myer  with  Lieutenant 
Frank  P.  Lahm  of  the  7th  Cavalry  in  charge, 
and  then  was  sent  to  Omaha  in  the  autumn  of 
1909,  with  I^ieutenants  R.  S.  Bamberger  of  the 
2nd  Cavalry,  John  G.  Winter  of  the  6th  Cav- 
alr)%  and  Oliver  A.  Dickinson  of  the  .5th  Infan- 
try in  charge.  These  officers  and  I^ieutenant 
Frank  P.  Lahm  were  subsequently  returned  to 
duty  with  their  respective  regiments,  because  of 
regulations    prescribing   a    time    limit    during 


204 


ing  the  development  of  civilian  aviation. 

During  the  jNIexican  outbreak  in  February 
and  JNIarch,  1911,  the  United  States  Army  had 
no  aeroplanes  to  send  to  the  Mexican  border. 
It  was  enabled  to  put  an  air  scout  at  the  dis- 
posal of  the  Government  through  the  courtesy 
of  ^Ir.  Robert  J.  Collier,  the  president  of  the 
Aero  Club  of  America,  who  loaned  the  army  his 
Wright  aeroplane.  With  this  machine  Lieu- 
tenant B.  D.  Foulois  and  Mr.  P.  O.  Parmalee, 
made  a  number  of  flights  along  the  Mexican 
border,  reconnoitering  and  carrying  messages 
from  General  Carter  to  jSIajor  George  O. 
Squier. 

During  the  winter  of  1911  I^ieutenant  Paul 
W.  Beck,  G.  E.  :M.  Kelley,  and  John  C.  Walker 
were  assigned  to  take  a  course  of  training  at  the 
Curtiss  Aviation  School  at  San  Diego,  Cal. 
They  were  assigned  to  duty  at  San  Antonio, 
Texas,  in  April,  1911,  to  fly  the  Curtiss  ma- 
chines acquired  by  the  United  States  Army. 

The  first  army  officer  to  be  granted  an  F.  A. 
I.  pilot's  certificate  was  Lieutenant  F.  P.  Labni. 
Lieutenants  II.  H.  Arnold  and  T.  deWitt  Mil- 
ling, Captain  Charles  DeF.  Chandler,  Lieuten- 
ant Benjamin  D.  Foulois,  Captain  Paul  W. 
Beck,  Lieutenant  R.  Carrington  Kirtland. 
Lieutenant  J.  W.  McClaskey,  Ijieutenant  Wil- 
liam C.  Sherman,  Lieutenant  Harry  Graiiam, 
and  Captain  Frederick  B.  Hennessey,  were  the 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


205 


next  ten  army  officers  to  obtain  a  pilot's  certifi- 
cate. 

By  the  Act  of  Congress  of  March  3,  1911, 
there  was  made  available  the  sum  of  $125,000 
for  army  aeronautics.  This  appropriation 
made  it  possible  to  establish  a  substantial  avia- 
tion camp  at  College  Park,  Md.  This  was 
moved  to  Augusta,  Ga.,  during  the  four  winter 
months  of  1912-13. 

Seven  aeroplanes  were  bought  for  the  United 
States  Army  in  1911.  Three  were  Wrights, 
three  were  Curtiss  machines,  and  one  was  a  Bur- 
gess biplane.  Important  experiments  were 
conducted  at  College  Park  during  1911-12,  in- 
cluding the  testing  of  the  Lewis  gun  and  the 
Scott  bomb-dropping  device;  also  experiments 
in  sending  wireless  messages  from  an  aeroplane, 
map-making,  and  other  pioneer  work. 

Early  in  1912  steps  were  taken  to  form  an 
aviation  section  in  the  Philippines,  and  one  aero- 
plane in  charge  of  Lieutenant  Frank  P.  Lahm 
was  sent  to  the  islands  for  that  purpose. 

Lack  of  funds  and  shortage  of  personnel  pre- 


•■^SOfSW^J^^R? 


The  Baldwin  dirigible,  first  and  only  dirigible  acquired  by  the 

United  States  Army  up  to  1917,  being  put  through 

the  tests,  August,  1908. 


Col.  (now  Gen.)  Squier  was  the  Chairman  of  the  Joint  Army 
and  Navy  Committee  ordered  to  conduct  the  tests  of  the  first 
Army  aeroplane  in  1908.  The  above  photograph  shows  the  aero- 
plane in  the  air  at  Fort  Meyer,  Va.,  on  September  12th,  1908, 
when  Orville  Wright  and  Col.  Squier,  who  was  the  first  passen- 
ger, made  a  flight  of  9  minutes  six  seconds,  which  was  a  record 
for  many  months. 

vented  expansion  of  the  air  service  and  exten- 
sion of  the  work  of  the  existing  organization. 

The  Act  of  August  24,  1912,  appropriated 
$100,000  for  the  purchase,  maintenance,  oper- 
ation, and  repair  of  aircraft.  Twelve  aero- 
planes were  bought  in  that  year.  Major  Sam- 
uel Reber  was  put  in  charge  of  the  Aeronautic 
Division. 

The  exact  number  of  machines  and  aviators 
and  the  distribution  of  the  United  States  Army 
Aviation  Squadron  in  June,  1913,  was  as  fol- 
lows: 

Machines 
OflScers        Training    High-powered 

Texas   City,   Texas    11  6  4 

San   Diego,   Cal 5  1  1 

Philippine    Islands    1  1  1 

Four  officers  were  on  temporary  duty  learn- 
ing to  fly,  and  Fort  Leavenworth,  Kansas,  had 
one  high-powered  machine. 


206 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


This  photograph,  which  was  taken  by  James  H.  Hare,  at  the  Mexican  border  in  1911,  shows  Col.   (now  Gen.)   Squier  on  the  left 

after   receiving   a   message   carried   by   Captain    (now    Brig.-Gen.)    Benjamin    D.    Foulois    and    Philip    O.    Parmalee. 

The  aeroplane  was  loaned  to  the  Army  by  Mr.  Robert  J.  Collier,  then  president  of  the  Aero  Club  of  America. 


The  general  equipment  of  this  handful  of  avi- 
ators consisted  of  the  barest  necessities.  The 
allowances  made  by  Congress  in  1911  and  1912 
were  too  meager  to  afford  more  than  the  neces- 
sar\'  aeroplanes,  tents,  and  spare  parts,  while  the 
1913  allowance  of  $12.5,000  was  bartely  sufficient 
to  replace  the  wornout  machines  and  afford 
maintenance.  It  was  not  possible,  therefore,  to 
acquire  motor-truck  repair-shops,  motor-trail- 
ers, extra  motors,  and  such  other  equipment  as 
was  absolutely  necessary  to  create  an  efficient 
organization. 

Lacking  funds,  the  Signal  Corps  was  unable 
to  replace  the  army  dirigible,  or  to  extend  the 
aerostatic  section.  Therefore  work  in  that 
branch  of  the  service  practically  ceased. 

Aeroplanes  were  first  u.sed  in  military  ma- 
noeuvers  in  August,  1912.  Two  machines  were 
assigned  to  these  manoeuvers,  in  charge  of  I.,ieu- 
tenants  B.  D.  Foulois  and  Harold  Geiger,  Cap- 
tain F.  B.  Hennessey,  lieutenant  T.  deW.  Mil- 
ling, and  Lieutenant  Harry  Graham. 


A  plan  to  give  the  army  120  aeroplanes  and  to 
establish  a  number  of  aviation  centers  was  pro- 
posed by  the  Secretary  of  War  in  a  special  re- 
port to  Congress  in  response  to  Resolution  444, 
House  of  Representatives,  March  26,  1912, 
(House  Document  No.  718,  62d  Congress, 
2d  Session),  but  Congress  took  no  action  on 
it. 

The  Act  of  March  2,  1913,  allowed  a  detail 
not  to  exceed  thirty  officers  of  the  line  of  the 
army  to  aviation  duty,  and  gave  extra  pay  to 
officers  engaged  in  flying. 

The  Act  approved  July  18th,  1914,  author- 
ized an  increase  of  the  Signal  Corps  by  the  addi- 
tion of  an  Aviation  Section.  Previous  to  the 
passage  of  this  Act  there  was  no  definite  provi- 
sion of  law  covering  the  duties  of  the  Signal 
Corps  with  respect  to  aviation.  Under  this  Act 
the  Aviation  Section  was  authorized  to  have 
sixty  officers  and  250  enlisted  men.  But  the 
shortage  of  officers  in  every  branch  of  the 
service  prevented  getting  more  than  half  that 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


207 


number   of   officers    for   the    aviation    section. 

In  1912  twelve  aeroplanes  were  bought,  and 
in  1913  eight  more  were  added.  In  1914  eleven 
machines  were  bought,  and  in  1915  twenty  more 
were  secured. 

The  following  table  gives  a  list  of  aeroplanes 
purchased  by  the  Signal  Corps  between  1908 
and  1916,  with  their  disposition: 

Aeroplanes  of  All  Types  Purchased  by  the 
Signal  Corps 


Date. 


Year 

1908 

19U 


1912 


Maker.  Disposition.  Date.  Total. 

Original  Wrightin  Smith.sonian  Institution 1 

Curtiss  Condemned    February,    1914 

Wriglit  do     do   

Do  Destroyed    by   accident.  .  .September,  1912 

Burgess  Condemned    February,    1914 

Curtiss  do     do 

Wright  Destroyed    by    accident ..  .August,    1913.. 

Curtiss  Condemned    June,  1914.  .  .  . 

Burgess  do     do    

Wriglit  Destroyed    by    accident.  .  .February,    1914 


Do    do  July,    1913 .... 

Do    do  November,  1913 

Do    do  October,  1913. . 

Do    do  November,  1913 

Curtiss do  April,  1913 .... 

Wright     do  June,    1914 .... 

Burgess    do  January,    1915. 

Do    do  September,  1913 

Wright     Condemned    June,    1914.... 

Do    do     do   

1913     Curtiss     do  do 

Do    do  October,  1914 . . 

Do    do  June,    1914.... 

Burgess     do  April,  1915.  .  .  . 

Do    do  January,    1915. 

Do    Out  of  repair    August,    1915.. 


1914 


Year.  Maker.  DLsposltion. 

Burgess-Dunne    .  In    commission     

Wright    Condemned    June,  1915.  . . . 

Burgess    Out  of  repair   

Do    Condemned    August,    1916.  . 

Curtiss     do     January,    1915. 

Do    do     November,  1915 

Martin    In    commission     

Do    Condemned    June,   1915.  . .  . 

Do    do     do   ...... 

Curtiss     In    commission     

Do    do     

Martin   do     

Do    do     

Burgess    Out  of  repair   

Curtiss In    commission     

Do    do     

Do    do     

Do    do     

Do    do     

Do    Condemned    October,  1915.  . 

Do    flo     August,    1915 .  . 

Do    In    commission     

Do    do     


Total. 


1915 


U 


Martin    do     

Do    do     

Curtiss do     

Do    do     

Martin    do     

Do    Undergoing  tests 

Do    In    commission     . 

Do    do     

Do    do     

Do    do     


12 


Total     

SUMMARY 

In   Smithsonian   Institution    

Destroyed  and  condemned    

Out   of   repair    

Now  in  service,  distributed  as   follows : 
Manila — 

Hydroplanes    4 

San    Diego — 

Flying  boats   2 

Training    machines 9 

Mexican   expedition    


20 


59 


1 
32 
3 


—      23 


Total 


59 


View  of  the  Signal  Corps  Aviation  Field,  College  Park,  Md.,  1912,  taken  from  an  Army  machine.     (From  "Flying.") 


208 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


The  first  tests  of  the 
now  famous  Lewis  gun 
were  made  by  United 
States  Aviators.  Cap- 
tain Charles  de  F.  Chan- 
dler and  Lieutenant  T. 
De  Witt  Milling  at  Col- 
lege Park,  Md.,  June  7th- 
Sth,  1912. 


The  Mexican  Campaign  Found  the  United 
States  Army  Unprepared  Aeronautically 

Our  utter  aeronautic  unpreparedness  was 
shown  in  ^larch,  1916,  when  Villa  raided  Co- 
lumbus, Xew  JNIexico,  and  other  American  lo- 
calities along  the  Mexican  Border,  killing 
Americans  and  destroying  property.  Villa 
raided  Columbus  on  March  9,  and  on  ^larch  11, 
Secretary  of  War  Baker  ordered  General  Scott, 
Chief  of  Staff,  to  instruct  General  Funston  to 
use,  as  far  as  possible,  the  Aero-Squadron  sta- 
tioned at  Fort  Sam  Houston,  San  Antonio, 
Texas,  in  his  expedition  against  Villa.  General 
Funston  realized  that  an  aeroplane  was  easilj' 
worth  5000  men  in  the  Mexican  campaign,  and 
that  scouts,  other  than  aerial,  faced  death  in 
crossing  the  Mexican  Border.  As  General 
Funston  pointed  out:  "Villa  parties  will  at 
times  surprise  these  scouting  parties.  In  ordi- 
nary warfare  our  men  might,  if  hopelessly  out- 
nunil)ered  and  resistance  were  futile,  surrender 
with  safety.  To  surrender  to  Villa,  however, 
would  be  worse  than  suicide.  Villa's  men  will 
kill  every  American  they  can  lay  their  hands 
pn.  Every  encounter  with  them  means  a  fight 
to  the  death  for  our  men." 

The  aero-squadron  at  Fort  Sam  Houston  in- 
cluded Captain  Benjamin  D.  Foulois,  Captain 


T.  S.  Dodd,  Lieutenant  J.  E.  Carberry,  Lieu- 
tenant T.  S.  Bowen,  Lieutenant  Ira  D.  Rader, 
Lieutenant  C.  C.  Chapman,  Lieutenant  H.  A. 
Dargue,  Lieutenant  Edgar  S.  Gorrell,  Lieuten- 
ant W.  G.  Kilner,  and  Lieutenant  R.  H.  Willis. 
These  aviators  joined  General  Pershing  at 
Casas  Grandes,  JSIexico,  about  110  miles  from 
the  border. 

The  squadron  had  only  eight  small,  low-pow- 
ered scout-aeroplanes,  not  suitable  for  flights  of 
over  50  miles  from  their  own  base  and  certainly 
not  adapted  for  the  difficult  conditions  under 
which  the  aviators  had  to  fly.  It  also  lacked 
general  equipment  required  to  keep  an  aero- 
squadron  in  the  field.  On  IMarch  27,  Secretary 
Baker  made  known  tliat  there  were  only  two 
aeroplanes  in  commission  for  use  by  the  Mexi- 
can Expedition,  and  that  General  Funston  had 
asked  for  more.  In  his  statement  Secretary 
Baker  said:  "The  wireless  coninnuiication  is 
reported  to  be  intermittent,  because  of  the  static 
conditions  in  the  electric  field  there.  For  this 
reason  additional  importance  is  given  to  the  re- 
quest for  aeroplane  facilities." 

Congress  was  asked  for  an  emergency  ap- 
propriation of  $500,000  for  aeroplanes.  Tliis 
sum  was  provided  on  March  28,  wlicii  the  Army 
Deficiency  Bill  passed  the  House  by  a  vote  of 
878  to  1. 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


209 


Lieutenant  Colonel  George  O.  Squier,  who 
had  been  military  attache  at  the  United  States 
Embassy  at  London,  was  appointed  to  take 
charge  of  the  Aeronautic  Division  of  the  United 
States  Army. 

Meanwhile  the  two  available  aeroplanes  were 
kept  in  daily  service  carrying  despatches  and 
reconnoitering  between  General  Pershing's 
camp  at  the  front  and  Columbus,  N.  M.  On 
April  22  a  despatch  stated  that  they  were  out  of 
commission,  being  repaired  at  Columbus,  and 
the  expeditionary  force  in  Mexico  was  without 
air  scouts. 

It  was  soon  evident  that  the  $.500,000  emer- 
gency appropriation  would  only  meet  a  frac- 
tion of  the  needs,  and  that  the  appropriation  of 
$1,222,000  asked  for  aeronautics  for  the  next 
fiscal  year  would  be  too  small  to  permit  start- 
ing a  substantial  air  service.  The  Aero  Club  of 
America  then  undertook  not  only  to  arouse  the 
country  to  the  need  of  a  substantial  air  service, 
but  also  to  create  a  reserve  of  trained  aviators. 

For  several  years  previously  the  Aero  Club  of 
America  had  been  urging  the  expansion  of  the 
army  air  service,  and  while  it  had  succeeded  in 
creating  what  little  interest  there  was  in  the 
subject,  it  was  far  from  achieving  its  aims. 
These  aims  were:  "To  give  the  United  States 
5000  aviators,  placing  this  country  in  the  posi- 


tion of  the  porcupine,  which  goes  about  its  daily 
peaceful  pursuits,  harms  no  one,  but  is  ever 
ready  to  defend  itself." 

Finding  it  impossible  to  get  authorization  for 
assigning  even  500  army  officers  to  aviation,  the 
Aero  Club  turned  to  forming  a  reserve  of  Na- 
tional Guard  officers  from  different  states.  Pa- 
triotic citizens  contributed  to  carrying  out  this 
plan. 

Mrs.  William  H.  Bliss  contributed  through 
the  club  the  funds  necessary  to  purchase  an  aero- 
plane and  train  officers  of  the  National  Guard 
of  New  York,  starting  an  aero  company  at 
Mineola,  Long  Island.  Lieutenant  Raynal  C. 
Boiling  was  commanding  officer  of  this  com- 
pany, which  some  months  later  gave  the  country 
a  score  of  good  aviation  reserve  officers. 

Messrs.  Emerson  McMillin,  T.  Jefferson 
Coolidge,  Barend  Van  Gerbig,  and  others,  made 
substantial  contributions,  and  the  Curtiss  Com- 
pany offered  to  train  an  officer  from  the  Na- 
tional Guard  of  each  state. 

When  Villa  raided  Columbus  the  Aero  Club 
offered  to  present  a  number  of  aeroplanes  to  the 
United  States  Army  and  to  supply  a  number  of 
volunteer  aviators.  This  offer  was  declined. 
But  when  the  two  aeroplanes  in  Mexico  went 
out  of  service  and  the  Carrizal  tragedy  took 
place,  a  request  was  sent  to  the  club  by  the  sig- 


The  Hangars  at  the  U.  S.  Army  Aviation  School  at  College  Park,  Md.,   1911. 


210 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


_!<!     "fijy. 


Four  of  the  aeroplanes  of  the  First  Aero  Squadron  at  Columbus,  New  Mexico. 


nal  officer  for  volunteers,  and  an  officer  was  as- 
signed to  work  with  the  club  in  mobilizing  civil- 
ian aeronautic  resources. 

The  list  of  volunteers  submitted  by  the  club 
included  about  fifty  civilian  aviators  and  the 
following  National  Guard  officers.  The  latter 
were  assigned  by  their  respective  Adjutant- 
Generals,  whose  names  also  follow : 

Arkansas. — Brigadier-General  Lloyd  Eng- 
land, the  Adjutant-General,  detailed  Second 
Lieutenant  Forrest  Ward  to  report  at  the  Cur- 
tiss  Aviation  School,  Newport  News,  Va.,  for 
training. 

Colorado. — Brigadier  General  John  Chase, 
the  Adjutant-General,  detailed  Lieutenant 
Cummings,  Signal  Corps,  National  Guard  of 
Colorado,  to  report  to  the  Curtiss  Aviation 
School,  Newport  News,  Va.,  for  training. 

Connecticut. — Brigadier  General  George  INI. 
Cole,  the  Adjutant-General,  detailed  Captain 
Ralph  L.  Taylor,  of  the  Connecticut  Coast  Ar- 
tillery of  Stamford,  Conn.,  to  report  to  the  Cur- 
tiss Aviation  School,  Newport  News,  Va.,  for 
training. 

Georgia. — Brigadier  General  Van  Holt 
Nash,  the  Adjutant-General,  detailed  Sergeant 
L.  V.  Smith  to  report  at  the  Curtiss  Aviation 
School,  Newport  News,  Va.,  for  training. 

Kentucky. — Brigadier  General  II.  Tandy 
Ellis,  the  Adjutant-General,  detailed  Lieu- 
tenant B.  Osborn,  of  the  Signal  Corps,  to  report 
at  the  Curtiss  Aviation  School,  Newport  News, 
Va.,  for  training. 

Minnesota. —  Brigadier  General  Fred  W. 
Wood,  the  Adjutant-General,  detailed  Geo.  M. 
Palmer  to  report  at  the  Curtiss  Aviation  School, 
Newport  News,  Va.,  for  training. 


Nehra.ika.~Br\frad\er  General  P.  L.  Hall, 
the  Adjutant-General,  detailed  Captain  Ralph 
E.  McMillin,  a  licensed  pilot,  to  report  at  the 
Curtiss  Aviation  School,  Newport  News,  Va., 
to  qualify  for  the  "Superior"  or  "Expert"  Li- 
cense issued  by  the  Aero  Club  of  America. 
This  was  in  response  to  the  Aero  Club  of  Amer- 
ica's telegrams  sent  out  March  12.  The  cost  of 
obtaining  tliis  license  was  borne  by  the  National 
Aeroplane  Fund. 

Netc  York.— The  Aviation  Company  of  the 
National  Guard  of  New  York,  which  had  been 
training  at  the  Mineola  Aviation  Field  com- 
prised the  following  gentlemen: 

Captain  Raynal  C.  Boiling;  Lieutenant  N. 
Carolin;  J.  E.  Miller;  A.  B.  Thaw,  2d  Master 
Signal  Electrician;  R.  J.  Gilmore;  First-Class 
Sergeants  P.  R.  Stockton,  F.  R.  Dick;  Quar- 
termaster Sergeant  W.  T.  Odell;  Sergeants  J. 
H.  Stevenson  and  E.  A.  Kruss;  Corporals  D. 
G.  Frost,  D.  R.  Noyes,  K.  B.  Hagerty,  W.  P. 
Willetts,  J.  R.  Speyers,  H.  H.  Salmon,  .Ir.,  P. 
J.  Roosevelt,  F.  .1.  Hoppin;  Privates  E.  C. 
Best,  F.  Boger,  Jr.,  K.  J.  Bevens,  W.  W.  Con- 
ant,  Jr.,  A.  M.  Craig,  J.  T.  Dwyer,  A.  L. 
Favre.  C.  C.  Goodrich,  P.  J.  Heiiry,  W.  T. 
Howell,  J.  F.  Hubbard,  W.  C.  Jenkins,  W.  J. 
Johnson,  R.  .1.  Knowlson,  E.  McCormick,  E. 
Martin.  I).  P.  Morse,  R.  M.  Olyphant.  Jr..  C. 
H.  Reynolds.  R.  F.  Russell,  P.  I).  Smith,  J.  D. 
Sullivan,  T.  F  Ward,  and  Trumpeter  W.  L. 
Rockwell. 

Buffalo,  N.  v. — Two  members  of  the  Buffalo 
Aero  Squadron  reported  at  the  Curtiss  Aviation 
.School,  Newport  News,  Va.,  to  receive  the  same 
course  of  training  given  the  militia  officers  of  the 
various  states,  detailed  for  instruction  by  the  Ad- 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


211 


jutant-Generals  of  their  respective  states. 
These  two  men  were:  Messrs.  Willis  G.  Hick- 
man and  Morgan  More. 

Lieutenant  Edward  Bagnell  was  detailed  to 
accompany  Captain  McMillin  to  Newport  News 
for  training. 

New  Hampshire, — Brigadier  General  C.  W. 
Howard,  the  Adjutant-General,  detailed  Lieu- 
tenant Ai'thur  J.  Coyle,  of  the  1st  Infantry,  to 
report  at  the  Curtiss  Aviation  School,  Newport 
News,  Va.,  for  training. 

North  Carolina. — Brigadier  General  L.  W. 
Young,  the  Adjutant-General,  detailed  liieu- 
tenant  D.  B.  Byrd,  of  Company  F,  2nd  In- 
fantry, to  report  at  the  Curtiss  Aviation  School, 
Newport  News,  Va.,  for  training. 

Ohio. — Brigadier  General  W.  B.  Hough,  the 
Adjutant  General,  detailed  Lieutenant  R.  H. 
Hoyer,  to  report  at  the  Curtiss  Aviation  School 
at  Newport  News,  Va.,  for  training. 


Oklahoma. — Brigadier  General  F.  M.  Can- 
ton, the  Adjutant-General,  detailed  Sergeant 
Harrison  Handley,  of  the  Infantry,  to  report  at 
the  Curtiss  Aviation  School,  Newport  News, 
Va.,  for  training. 

Oregon. — Brigadier  General  Geo.  H.  White, 
the  Adjutant-General,  detailed  Captain  Frank 
W.  Wright  to  report  to  the  Curtiss  Aviation 
School  at  San  Diego,  California,  for  training. 

Chief  Mechanic  Bairn,  an  experienced  avi- 
ator, was  detailed  to  accompany  Captain 
Wright  to  San  Diego  to  qualify  for  the  "Su- 
perior," or  "Expert,"  License  issued  by  the 
Aero  Club  of  America. 

Tennessee. — Brigadier  General  C.  B.  Rogan, 
the  Adjutant-General,  detailed  Lieutenant 
Curry  A.  McDaniels,  of  the  Infantry,  to  report 
at  the  Curtiss  Aviation  School,  Newport  News, 
Va.,  for  training. 

Texas. — Brigadier  General  H.   Hutchings, 


Mustering  into  the  Federal  Service  the  First  Aero  Company,  X.  Y.  X.  G.,  at  Mineola,  which  was  started  tliicJUL'li  tlic  icmtrihu- 
tion  of  Mrs.  William  H.  Bliss  and  trained  at  private  expense,  dose  to  $60,000  contributed  largely  through  the  Aero  Club  of 
America.  Most  of  these  men  became  members  of  the  Signal  Officers  Reserve  Corps.  The  personnel  of  the  Aero  Company,  which 
includes  many  members  of  prominent  New  York  families,  as  mustered  in,  was  as  follows:  Captain  Raynal  C.  Boiling,  Lieutenant 
N.  Carolin,  J.  E.  Miller,  A.  B.  Thaw,  3nd  Master  Signal  Electrician;  R.  J.  Gilmore;  First-CIass  Sergeants,  P.  R.  Stockton,  F.  R. 
Dick;  Quartermaster  Sergeant,  W.  T.  Odell;  Sergeants,  J.  H.  Stevenson,  E.  A.  Kruss;  Corporals,  D.  G.  Frost,  D.  R.  Noyes, 
E.  B.  Hagerty,  W.  P.  Willets,  J.  R.  Speyers,  H.  H.  Salmon,  Jr.,  P.  J.  Roosevelt,  F.  J.  Hoppin;  Privates,  E.  C.  Best,  F.  Boger,  Jr., 
K.  J.  Bevens,"w.  W.  Conant,  Jr.,  A.  M.  Craig,  J.  T.  Dwyer,  A.  L.  Favre,  C.  C.  Goodrich,  P.  J.  Henry,  W.  T.  Howell,  J.  F.  Hubbard, 
W.  C.  Jenkins,  W.  J.  Johnson,  R.  J.  Knowlson,  E.  McCormick,  E.  Martin,  D.  P.  Morse,  R.  M.  Olyphant,  Jr.,  C.  H.  Reynolds, 
R.  F.  Russell,  P.  D.  Smith,  J.  D.  Sullivan,  T.  F.  Ward,  and  Trumpeter,  W.  L.  Rockwell. 


212 


TEXTBOOK  OF  MILITARY  AEROXAUTICS 


i?*- 


A  squadron  of  American  training  uiacliincs  at  one  of  the  Army  Aviation  Schools  in  191G. 


the  Adjutant-General,  detailed  Lieutenant 
Byron  McMuUen  to  report  at  the  Curtiss  Avia- 
tion School,  Xewport  News,  Va.,  for  training. 

Vermont. — Brigadier  General  Lee  S.  Tillot- 
ton,  the  Adjutant-General,  detailed  Lieutenant 
Harold  P.  Sheldon,  of  the  1st  Infantry,  to  re- 
port at  the  Curtiss  Aviation  School,  Newport 
News,  Va.,  for  training. 

Virginia. — Brigadier  General  W.  W.  Sales, 
the  Adjutant-General,  detailed  Corporal 
Greenhow  Johnston,  of  the  Signal  Corps,  Vir- 
ginia National  Guard,  to  report  at  the  Curtiss 
Aviation  School,  Newport  News,  Va.,  for  train- 
ing. 

West  Virginia. — Brigadier  General  John  C. 
Bond,  the  Adjutant-General,  detailed  Lieu- 
tenant Howard  F.  Wehrle,  to  report  at  the  Cur- 
tiss Aviation  School,  Newport  News,  Va.,  for 
training. 

As  the  United  States  Army  had  no  authoriza- 
tion to  enroll  civilians  in  an  aerial  reserve  corps, 
the  latter  applied  to  the  Aero  Club  of  Amer- 
ica. Applications  were  received  at  the  rate  of 
one  thousand  per  month.  The  club  urged  Con- 
gress to  provide  for  an  aerial  reserve,  and  on 


May  25,  1916,  Mr.  Alan  R.  Hawley,  the  presi- 
dent of  the  club,  flew  from  New  York  to  Wash- 
ington with  Victor  Carlstrom,  carrying  a  special 
edition  of  the  "New  York  World"  containing 
indorsements  from  governors  and  other  state 
authorities  of  the  plan  to  train  2000  aviators. 
As  soon  as  the  National  Defense  Act  of  June  3, 
1916,  was  passed, — an  act  which  provided  for 
the  enrolling  of  officers  and  men  in  the  Officers' 
and  Enlisted  Men's  Reserve  Corps, — a  commit- 
tee of  the  club,  consisting  of  jNIessrs.  Alan  R. 
Hawley,  Congressman  Murray  Hulbei't,  Ralph 
Pulitzer,  Robert  J.  Collier,  and  the  writer, 
waited  on  President  Wilson  and  urged  him  to 
authorize  the  organization  of  the  Aerial  Reserve 
Corps. 

On  July  13,  1916,  a  telegram  from  the  White 
House  advised  the  club  that  the  President  had 
authorized  the  organization  of  the  Aerial  Re- 
serve Corps. 

In  the  meantime  a  most  energetic  campaign 
of  public  education  was  conducted  by  the  club 
to  bring  about  an  increase  of  the  aeronautical 
appropriation  from  $1,222,000,  as  estimated,  to 
$29,000,000,  the  sum  urged  by  the  club.     An 


Some  of  the  arroplanes  In  uhp  nt  the  Army  Avliitlon  Field  at  Sun  Oiego  In  1916. 


i 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


218 


The  International  Aircraft  Standardization  Committee,  which  met  in  Washington,  August  14—15,  for  the  first  time.  Seated, 
left  to  right,  F.  G.  Diffin,  U.  S.,  Chairman;  G.  I..  Xorris,  U.  S.;  Lieut.  M.  Mignot,  France;  Capt.  J.  Herck,  France;  A.  B.  Rogers, 
England,  and  S.  G.  Payne,  England.  Standing,  P.  D.  Merica,  Bureau  of  Standards;  F.  G.  Ericson,  Canada;  W.  F.  Prentice,  Eng- 
land; Capt.  A.  Pomilio,  Italy;  J.  S.  MacGregor,  U.  S.;  H.  Chase  and  Dr.  G.  K.  Burgess,  both  of  the  U.  S.  Bureau  of  Standards. 


amendment,  proposed  by  Congressman  Murray 
Hulbert  when  it  first  came  before  the  House,  to 
increase  the  appropriation  to  $14,000,000,  was 
defeated  on  a  point  of  order.  An  amendment 
proposed  by  Congressman  James  Mann,  was 
adopted,  however.  This  amendment  increased 
the  appropriation  to  $3,500,000.  Senator 
George  E.  Chamberlain,  the  chairman  of  the 
Committee  on  Mihtary  Affairs,  next  introduced 
the  amendment  in  the  Senate,  and  while  it  met 
with  difficulties,  it  finally  was  adopted,  the  ap- 
propriation allowed  being  $13,861,000. 

This  appropriation  permitted  the  Signal 
Corps  to  develop  the  aeronautic  division  on  a 
more  substantial  basis,  and  gave  this  country  a 
year's  start  toward  improved  aerial  develop- 
ments. 

The  Chief  Signal  Officer,  in  his  report  dated 
October  3,  1916,  has  stated  that  there  were 
thirty-nine  officers  detailed  in,  and  forty-six  stu- 
dents attached  to,  the  Aviation  Section. 

An  official  report  issued  October  20  stated 
that  the  Aviation  Section,  "ordered  175  aero- 
planes for  the  Army  and  soon  will  order  100 
hydroaeroplanes  and  100  training  school  ma- 
chines to  be  used  in  training  the  Army  and  the 
National  Guard."  The  report  also  announced 
that  orders  had  been  signed  on  that  date  for  the 
formation  at  San  Diego  of  the  Second  and 
Third  Aero  Squadrons  for  the  Army, 


The  Report  stated  further  that  "the  Army 
has  45  junior  military  aviators,  with  a  tactical 
staff  of  six  officers,  has  38  officers  under  instruc- 
tion at  San  Diego,  where  they  have  been  turned 
out  at  the  rate  of  eight  a  month. 

"Major  Charles  de  F.  Chandler  of  the  Signal 
Corps,  who  has  had  practical  experience  in  bal- 
looning, has  been  placed  in  charge  of  all  military 
balloon  work,  and  bids  have  been  advertised  for 
four  army  balloons,  two  spherical  and  two  kite. 
The  balloon  section  may  be  established  at 
Omaha  or  at  Akron. 

"The  Army  will  train  officers  in  flying  at  San 
Diego,  where  it  has  eleven  training  machines 
which  are  to  be  increased  by  eighteen  hydroaero- 
planes. There  are  six  machines  at  the  Mineola 
training  school  on  Long  Island,  and  twelve  un- 
der order  for  use  there.  There  are  four  ma- 
chines at  the  Chicago  training  station  and 
twelve  ordered.  The  army  bill  appropriated 
$300,000  for  purchase  of  land  in  California  for 
aviation  school  purposes  and  $300,000  for  an- 
other large  tract.  A  special  board  is  now  consid- 
ering the  selection  of  the  second  site  in  the  East. 

"The  army  has  only  one  thoroughly  equipped 
areo  squadron.  It  is  at  Columbus,  N.  M.,  and 
has  twelve  160-horse-power  reconnoissance  type 
of  Curtiss  aeroplanes,  one  Curtiss  twin-tractor 
of  200  horse-power.  The  army  also  has  one 
aero  company  stationed  in  the  Philippines  for 


214 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


coast  defense  work.  It  will  be  raised  to  aero 
squadron  strength." 

General  Orders  Xo.  55  provided  that  the  Re- 
serve OjBicers  of  the  Aviation  Section  of  the  Sig- 
nal Corps  should  consist  of  296  officers.  An 
order  issued  September  8,  1916,  limited  the 
number  of  National  Guard  Officers  to  be  trained 
in  aviation  at  army  schools  to  fifty. 

On  October  11,  1916,  President  Wilson  au- 
thorized the  creation  of  the  Council  of  National 
Defense  and  appointed  seven  civihan  members 
of  the  Advisory  Committee  of  the  Council,  as 
follows :  Daniel  Willard ;  Samuel  Gompers ;  Dr. 
Franklin  H.  Martin;  Howard  E.  Coffin;  Ber- 
nard Baruch;  Dr.  HoUis  Godfrey;  Julius  Ro- 
senwald. 

On  February  7,  1917,  when  it  became  known 
that  the  House  Committee  on  Military  Affairs 
in  reporting  the  appropriation  for  Army  aero- 
nautics for  the  ensuing  year  had  allowed  only 
$8,000,000  for  equipment  and  $1,000,000  for 
aeronautic  stations,  the  Aero  Club  of  America 


started  another  campaign  of  public  education 
to  get  the  appropriation  inci'eased  to  a  minimum 
of  $50,000,000  and  to  insure  the  training  of 
2000  aviators  during  1917. 

After  a  meeting  of  the  National  Advisory 
Committee  on  Aeronautics  held  March  20-31  an 
official  statement  was  issued  outlining  the  plans 
of  the  Ai-my  and  Navy  regarding  the  number  of 
aviators  to  be  trained  and  machines  to  be  or- 
dered, which  read  in  part  as  follows : 

"There  are  many  estimates  of  our  reasonable 
needs,  and  the  one  herewitli  presented  has  been 
prepared  after  conferences  with  as  many  men  as 
could  be  reached  who  have  experience  or  judg- 
ment quahfying  them  to  express  an  opinion,  and 
after  obtaining  as  many  data  as  possible  from 
Europe. 

"Tentative  estmiate  of  annual  requirements 
of  aeroplanes  ( assumed  to  be  possible  of  accom- 
plishment in  1916) : 

"Attached  to  an  army  of  1,000,000  men,  1,000 
planes  and  1,000  aviators. 


Thl«  photo^aph  shows  the  First  Aircraft  Production  Board  in  its  mcetinff  room  in  the  Munsey  Huildinp,  Wnshintrton,  I).  C. 
Prom  left  to  rl(fht:  A.  G.  Cahle,  Secretary  of  the  Board;  R.  L.  Montgomery,  .Sidney  I).  Waldon,  K.  A.  Heeds.  Hear  Admiral 
David  W.  Taylor,  Chief  of  the  Bureau  of  Construction  and  Repair,  U.  S.  N.;  Brigadier-General  George  O.  Squler,  Chief  Signal 
Oflcer,  U.  S.  A.|  Howard  E.  Coffin,  Chairman  of  the  Board. 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


215 


Officers  at  the  Mineola  aviation  station.  From  left  to  ripht,  sitting:  Capt.  li.  L.  Taylor,  oliircr  in  eliarge  ul'  flying;  l.L.  Cliurlcs 
Reed,  first  aero  reserve  squadron;  Capt.  P.  A.  Carroll,  first  aero  reserve  squadron;  Capt.  Frank  T.  Coffyn,  S.  O.  R.  C. ;  Maj. 
W.  G.  Kilner,  C.  O.,  S.  C.  A.  S.,  Mineola;  Capt.  S.  W.  Fitzgerald,  Commanding  officer;  Capt.  Henry,  Adjutant,  S.  C.  A.  S.,  Mine- 
ola. From  left  to  right,  standing:  Lt.  Stroman,  photographic  department;  I,t.  Jones,  training  department;  I,t.  L.  C.  Ricker,  quar- 
termaster; Lt.  W.  P.  Willetts,  technical  department;  Lt.  Olyphant,  fir.st  aero  reserve  squadron;  Lt.  B.  O.  Watkins,  supply  depart- 
ment; Lt.  D.  R.  Wheeler,  supply  officer;  Lt.  H.  H.  Simons,  training  department;  Lt.  Montarial,  instructor  detailed  from  French 
F.  C;  Lt.  Page,  technical  department. 


"Attached  to  our  fleet  at  sea,  200  planes  and 
200  aviators. 

"For  harbor  and  seaport  defense,  800  planes 
and  800  aviators. 

"Total,  2,000  planes  and  2,000  aviators. 

"For  training  pilots  (worn  out  or  broken), 
2,000  planes  and  400  aviators. 

"Total,  4,000  planes  and  2,400  aviators." 

Seven  weeks  after  the  United  States'  entry  in 
the  war,  on  May  21,  1917,  there  was  created  the 
Aircraft  Production  Board,  in  the  Council  of 
National  Defense,  the  personnel  of  which  was 
as  follows:  Howard  E.  Coffin,  Chairman; 
Brig.  Gen.  George  O.  Squier,  Chief  Signal 
Officer,  U.  S.  A.;  Rear  Admiral  David  M. 
Taylor,  of  the  navy;  S.  D.  Waldon;  E.  E. 
Deeds;  and  R.  L.  Montgomery. 

The  preliminary  announcement  of  the  Air- 
craft Production  Board  was  as  follows : 

"We  now  believe  America  has  started  on  the 
right  road  toward  working  out  her  destiny  in  the 
air  and  taking  the  place  to  which  her  capacity 
•entitles  her  and  which  the  world  expects  of  her. 
We  have  been  in  constant  touch  for  weeks  with 


the  aircraft  manufacturers  on  the  problem  of 
the  quantity  production  of  machines,  and  the 
Government  authorities  are  already  signing 
contracts  for  as  many  machines  as  our  present 
appropriation  permits.  The  United  States  can 
depend  on  a  minimum  of  3500  aircraft  of  all 
types  for  the  first  year,  if  Congress  authorizes 
us  to  proceed.  The  program  we  now  have  in 
mind  would  provide  for  both  training  and  com- 
bat machines. 

"The  country  has  made  progress  in  develop- 
ing aviators.  Last  month  a  group  of  army  offi- 
cers visited  the  training  camp  of  the  Royal  Fly- 
ing Corps  at  Borden,  Ontario,  one  of  the  four 
camps  established  in  Canada  and  the  aviation 
school  at  Toronto,  where  cadets  are  trained  un- 
der militaiy  discipline  for  the  service.  In  these 
schools  there  has  been  incorporated  the  latest 
European  experience  in  the  development  of  this 
new  art  of  the  air. 

"Our  officers  were  deeply  impressed  with  their 
observations,  and  as  a  result  we  called  together 
here  the  heads  of  six  prominent  engineering 
schools  which  also  have  military  training,  and 


216 


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made  plans  to  estahlisli  u  similar  system  in  the 
United  States.  The  six  institutions  are  the 
Universities  of  California,  Texas,  Illinois,  Ohio, 
JMassachusetts  Institute  of  Technology,  and 
Cornell  University.  Three  technical  instruct- 
ors from  each  of  these  places  were  sent  to 
Toronto.  They  returned  on  May  8  after  a 
comprehensive  study  of  the  course  given  there, 
prepared  to  teach  it  themselves.  On  May  10 
these  six  engineering  schools  opened  similar 
cadet  aviation  schools  at  their  respective  insti- 
tutions. At  the  end  of  two  months  of  this  pre- 
liminary work,  the  cadet  is  given  a  final  test  to 
determine  whether  he  shall  go  on  to  the  aviation 
camp. 

"The  manufacturing  capacity  can  easily  he 
doubled  the  second  year.  A  prominent  Brit- 
ish General  has  asserted  that  America's  great- 
est contribution  to  the  war  will  be  aircraft  and 
aviators.  We  believe  that  once  started  upon 
quantity  production,  American  mechanical  gen- 
ius will  overcome  any  present  obstacles  to  the 
progress  of  the  art." 

The  Deficiency  Bill  to  provide  for  the  Army's 
needs  at  that  time  carried  an  appropriation  of 
only  $54,000,000  for  aeronautics. 

Appreciating  the  fact  that  the  plans  for  the 
building  of  our  Air  Forces  on  a  scale  propor- 
tionate to  the  need  were  restricted  by  lack  of 
prospects  to  get  sufficient  appropriations  and 
believing  that  the  American  ])ublic  would  favor 
the  adoption  of  a  plan  extensive  enough  to  pro- 
vide for  the  training  and  ecjuipping  of  ten  thou- 
sand aviators  and  sending  tens  of  thousands  of 
aeroplanes  to  the  Allies,  the  Aero  Club  of 
America  undertook  to  get  public  support  for 
such  a  plan. 

The  canipaign  started  a  few  days  after 
the  announcement  of  the  Aircraft  Production 
Board.  The  slogan  "We  m ust  Strike  Germani/ 
Through  the  Air"  was  adopted. 

In  the  first  statement  Mr.  Alan  R.  ITawley, 
the  President  of  the  Aero  Club  of  America, 
pointed  out  that,  "Germany's  U-boat  warfare 
and  the  necessity  of  keeping  the  German  Heet 
Imttled  up  are  occupying  the  navies  of  the  Allies 
and  no  decisive  victory  over  the  Germans  is  ex- 
pected in  naval  actions  in  the  near  future. 
Likewise  advances  against  the  Germans  on  land 


are  slow,  and  Germany  has  seemed  able  so  far 
to  always  throw  new  thousands  of  men  and  new 
lines  of  trenches  and  countless  guns  to  meet 
the  advance  of  the  Allies.  The  only  victories 
on  the  part  of  the  Allies  so  far  have  been  as  a 
result  of  supremacy  of  the  air,  as  a  result  of  the 
matching  of  skilful,  daring  Allied  aviators 
against  German  aviators  and  observation  bal- 
loons; the  recent  British  and  Italian  victories 
wei-e  preceded  by  countless  aerial  fights  in  which 
hundreds  of  aviators  took  part,  and  it  was  not 
until  the  skies  had  been  cleared  of  German  avi- 
ators and  of  German  observation  balloons — and 
the  Germans  were  thereby  deprived  of  the 
aerial  eyes  of  the  infantry,  of  the  aerial  scouts, 
and  the  Allies'  aviators,  being  masters  of  the  air, 
could  follow  the  movements  of  the  enemy  and 
locate  their  batteries  and  their  strongholds,  that 
the  victories  became  possible. 

"While  the  United  States  is  beginning  to  help 
substantially  now,  effective  help  of  the  kind  that 
leads  to  permanent  victory  can  only  come  at  the 
end  of  months  of  preparation,  and  in  consider- 
ing in  which  way  we  can  best  prepare  to  help  to 
achieve  permanent  victories  it  is  found  that  the 
aerial  branch  of  the  service  affords  the  greatest 
possibilities.  British,  French,  Russian,  Italian 
and  American  authorities  who  have  studied  the 
matter  closely  have  come  to  the  conclusion  that 
the  addition  of  10,000  aviators  to-day  to  the 
Allies'  present  aerial  forces  would  insure  blind- 
ing the  German  batteries  and  preventing  Ger- 
man aviators  from  conducting  operations  over 
or  near  the  Allies'  lines.  An  additional  10,000 
aviators  would  make  it  possible  to  conduct  aerial 
raids  on  a  large  scale  and  to  strike  Germany  in 
the  most  vital  places,  to  strike  hard  enough  to 
lead  to  permanent  victories." 

A  billion  .dollar  appropriation  was  urged  for 
Army  aeronautics.  It  soon  became  evident 
that  the  pul)lic  favored  the  appropriation  of  this 
sum. 

One  of  the  most  important  factors  in  creating 
favorable  public  sentiment  for  this  appropri- 
ation was  the  hearings  held  by  the  Senate  Sub- 
Committee  on  Military  Affairs  on  the  Shep- 
pard-Hulbert  Bill  to  create  a  Department  of 
Aeronautics.  This  brought  forth  the  endorse- 
ment of  leading  authorities  of  not  only  the  plan 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


217 


to  train  thousands  of  aviators  and  build  tens  of 
thousands  of  aeroplanes,  but  also  strong  general 
endorsements  of  the  Sheppard-Hulbert  Bill. 

The  hearings  began  June  12th,  and  lasted  for 
two  weeks.  Those  who  testified  before  the  Sen- 
ate Sub-Committee  of  the  House  of  Representa- 
tives, and  endorsed  the  plan  to  establish  a  De- 
partment of  Aeronautics,  were  as  follows; 
Rear  Admiral  Robert  E.  Peary:  Major  L.  W. 
B.  Rees,  of  the  British  Royal  Flying  Corps, 
member  of  the  British  Commission  in  the  United 
States;  Howard  E.  Coffin,  Chairman,  Aircraft 
Production  Board;  Brigadier  General  George 
O.  Squier,  Chief  Signal  Officer,  U.  S.  A.;  Alan 
R.  Hawley,  President,  Aero  Club  of  America; 
Henry  Woodhouse,  Henry  A.  Wise  Wood, 
Augustus  Post,  Rear  Admiral  Bradley  A. 
Fiske ;  Lieut.  Rumsey  and  Lieut.  Prince,  mem- 
bers of  the  Lafayette  Flying  Corps;  J.  Bernard 
Walker;  F.  H.  Allen,  one  of  the  Directors  of 
the  Lafayette  Flying  Corjjs;  INIajor  General 
Goethals;  Joseph  A.  Steinmetz,  President  of 
the  Aero  Club  of  Pennsylvania. 

The  forceful  statements  made  by  these  au- 
thorities were  pubhshed  daily  by  the  press 
throughout  the  United  States  and  brought  out 
hundreds  of  editorials  urging  prompt  action  and 
large  appropriations. 

Brigadier  General  George  O.  Squier,  the 
Chief  Signal  Officer  of  the  Army,  in  endorsing 
the  aerial  preparedness  program  said,  in  part: 

"The  way  to  beat  Germany  is  to  flood  the 
air  with  aeroplanes.  Take  the  war  out  of  the 
trenches  and  off  the  ground.     Put  it  in  the  air." 

On  June  18th  Secretary  Baker  came  out  for 
a  vast  air  fleet. 

"The  War  Department  is  behind  the  aircraft 
plans  with  every  ounce  of  energy  and  enthusi- 
asm at  its  command,"  said  Secretary  Baker. 

"The  aircraft  program  seems  by  all  means 
the  most  effective  way  in  which  to  exert  Amer- 
ica's force  at  once  in  telling  fashion. 

"We  can  train  thousands  of  aviators  and  build 
thousands  of  machines  without  interfering  in  the 
slightest  with  the  plans  for  building  up  our 
armies  and  for  supplying  the  allies  with  food 
and  munitions.  To  train  and  equip  our  armies 
and  send  them  abroad  will  take  time,  however, 
and  in  the  meantime  we  can  be  devoting  to  this 


most  important  service  vast  quantities  of  pro- 
ductive machinery  and  skilled  labor  which  other- 
wise could  not  be  contributing  to  the  nation's 
cause  in  full  proportion  to  its  capacity. 

"The  aircraft  j)lans  meet  the  demands  of  the 
situation.  Under  existing  conditions  of  fight- 
ing, where  the  allies  and  the  Germans  are  fight- 
ing on  practically  even  terms  as  regards  man 
power  and  aircraft,  the  addition  which  we  can 
contribute  to  the  allied  air  forces  will  be  propor- 
tionately of  far  greater  value  than  the  immediate 
aid  which  we  can  furnish  on  land.  According 
to  the  best  obtainable  information,  there  are 
about  7,000,000  men  on  the  western  front  to- 
day. The  addition  of  a  few  infantry  units, 
while  of  great  moral  value,  is  of  little  use  in 
forcing  a  decision.  A  few  thousand  trained 
aviators,  however,  with  the  machines  for  their 
use,  may  spell  the  whole  difference  between  vic- 
tory and  defeat.  The  supremacy  of  the  air,  in 
modern  warfare,  is  essential  to  a  successful 
Army.  America  must  make  sure  that  the  Al- 
lies and  not  Germany,  secure  the  permanent 
domination  of  the  air,  and  that  within  the 
year." 

On  June  22  President  Wilson  himself  en- 
dorsed the  movement,  in  the  following  letter  to 
Secretary  Baker: 

The  White  House, 
Washington. 
My  Dear  Mr.  Secretary: 

I  have  your  letter  of  yesterday  about  the  produc- 
tion of  aircraft  and  the  training  of  men  to  operate 
them,  and  want  to  say  that  I  am  entirely  willing  to 
back  up  such  a  program  as  you  suggest.  I  hope  that 
you  will  present  it  in  the  strongest  possible  way  to  the 
proper  committee  of  the  Congress. 
Cordially  and  sincerely  yours, 

(Signed)  Woodrow  Wilson. 

Hon.  Newton  D.  Baker, 
Secretary  of  War. 

A  bill  appropriating  $640,000,000  was  intro- 
duced and  passed  the  House  of  Representa- 
tives on  July  14,  without  a  dissenting  vote.  It 
passed  the  Senate  on  July  21,  and  was  signed 
by  President  Wilson  July  24. 

The  estimate  showed  that  only  $363,000,000 
was  to  be  spent  for  aeroplanes,  the  rest  going  to 
pay  for  the  service  squadron,  supply  squadrons, 
training  stations,  machine  guns,  etc.,  and  that 


218 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


the  number  of  aeroplanes  to  be  ordered  under 
that  appropriation  would  be  only  about  22,000, 
a  good  portion  of  which  would  be  training 
machines  needed  for  the  training  of  aviators. 

The  Aero  Club  of  America  thereupon  imme- 
diately started  a  campaign  to  make  known  the 
necessity  of  an  additional  appropriation  of 
$1,000,000,000  to  build  the  thousands  of  large 
warplanes  needed  to  conduct  major  aerial  op- 
erations against  the  German  bases. 

Being  told  that  the  shortage  of  tonnage  would 
preclude  shipping  thousands  of  aeroplanes  to 
France,  the  Aero  Club  started  to  develop  plans 
for  delivering  the  aeroplanes  by  flying  them 
across  the  Atlantic. 

Aircraft  Board  Created 

It  became  evident  that  to  get  quicker  action 
and  remove  confusion  in  the  production  of  air- 
craft it  would  be  best  to  have  an  Air  Board  with 
full  authority,  or  better  still,  a  separate  De- 
partment of  Aeronautics.  The  Aero  Club  of 
America  had  recommended  the  separate  de- 
partment of  aeronautics  in  1915,  and  urged  it 
continuously  ever  since. 

Getting  an  Air  Board  with  sufficient  author- 
ity the  Aircraft  Production  Board  and  the 
Signal  Corps  were  prompt  in  acting  and  carry- 
ing the  plans  into  effect.  Their  work  in  estab- 
lishing and  putting  into  operation  huge  train- 
ing aviation  camps  was  extraordinary.  Carry- 
ing out  the  aircraft  production  program  was 
slower. 

Among  the  most  striking  accomplishments 
were  the  developing  of  the  "Liberty  motor"  de- 
signed l)y  Messrs.  J.  C.  Vincent  and  E.  S.  Hall, 
and  the  creation  of  the  International  Aircraft 
Standards  Board  with  Mr.  F.  G.  Diffin  as  chair- 
man, was  a  step  towards  it.  A  bill  to  create 
the  Air  Board  was  introduced  in  the  Senate  by 
Senator  Morris  Sheppard  of  Texas  and  in  the 
House  of  Representatives  by  Congressman 
^lurray  Hulbert  of  New  York.  It  passed  the 
Senate  on  September  12  and  the  House  on  Sep- 
temljer  26.  It  was  signed  by  President  Wilson 
onOctol)er  1st,  1917. 

The  act  creating  the  Aircraft  Board  and  the 
endorsements  of  Secretary  Baker  and  Secretary 


Daniels  may  be  found  in  "Flying"  for  Sep- 
tember, 1917. 

Unfortunately  the  provisions  contained  in 
Section  4  and  Section  5  of  the  Act  confined  this 
Board  to  a  merely  advisory  capacity  and  pre- 
vented its  getting  an  organization  adequate  to 
do  the  important  work  of  building  Air  Forces 
extensive  enough  to  cope  with  the  fastly  devel- 
oping German  Air  Forces. 

The  following  were  appointed  on  the  new 
Aircraft  Board:  Howard  E.  Coffin,  chairman; 
Major-General  George  O.  Squier;  Colonel  E. 

A.  Deeds;  Colonel  R.  L.  Montgomery;  Ad- 
miral D.  W.  Taylor;  Captain  Noble  E.  Irwin; 
Lieutenant-Commander  A.  K.  Atkins;  R.  F. 
Howe,  appointed  November  6,  1917;  and  H. 

B.  Thayer,  appointed  February  26,  1918. 
While  these  plans  were  being  made  in  the 

United  States,  two  changes  took  place  in  the 
situation  in  Europe,  as  follows: 

1.  Aerial  warfare  became  more  and  more 
intensified.  Aerial  combats  became  more  nu- 
mez'ous;  the  employment  of  aeroplanes  to  attack 
infantry  and  artillery  formations  grew  more 
and  more  extensive;  bombing  at  short-  and 
long-distance  range  became  an  every-day  mat- 
ter. This  greatly  increased  the  number  of 
aeroplanes  in  use,  and  more  than  quadrupled 
the  percentage  of  casualties  among  aviators  and 
the  loss  of  aeroplanes  due  to  different  causes. 

2.  The  Italian  reverses  and  the  Russian 
collapse  brought  about  serious  conditions,  ne- 
cessitating a  much  greater  contribution  in  air- 
craft and  aviators  from  the  United  States  than 
was  planned  and  greater  speed  in  carrying  out 
the  plan.  A  committee  of  the  Aero  Club  of 
America,  headed  by  Mr.  Alan  R.  Hawley,  the 
])resident  of  the  club,  and  including  Congress- 
man Murray  Hulbert,  Admiral  I'eary,  and  the 
writer,  called  on  some  of  the  Washington  au- 
thorities to  urge  the  necessity.  We  found  the 
authorities  divided  in  two  groups:  those  who 
felt  certain  that  Congress  would  give  additional 
appropriations  for  aeronautics  immediately 
after  convening  in  December;  those  who  be- 
lieved the  program  under  way  to  be  sufficient  to 
meet  the  changed  condition,  and  would  not  con- 
sider increasing  it. 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


219 


It  soon  became  apparent  that  the  Russian 
and  Itahan  reverses  could  have  been  prevented 
had  those  countries  had  about  two  hundred 
additional  warplanes  each,  and  that  an  auxiliary 
air  fleet  was  needed  to  meet  the  swift  manceuvers 
of  the  enemy.  At  the  annual  meeting  of  the 
Aero  Club  of  America  on  November  12,  1917, 
the  following  resolution  was  adopted,  which  was 
transmitted  to  President  Wilson;  Secretary  of 
War  Newt(ni  D.  Baker;  Secretary  of  the  Navy 
Josephus  Daniels;  Mr.  Howard  E.  Coffin,  the 
chairman  of  the  Aircraft  Board;  and  Major- 
General  George  O.  Squier,  the  chief  signal 
officer : 

Whereas,  Tlio  greatest  difficulty  of  the  Allies  has 
been  to  move  their  forces  fast  enough  to  meet  unex- 
pected German  attacks  on  weak  points  of  the  Allied 
lines,  and  to  overcome  the  advantage  which  the  Ger- 
mans have  of  being  able  to  transport  large  bodies  of 
troo])s,  ammunition  and  supplies  from  one  point  to 
another  by  interior  lines  ;  and 

Whereas,  It  is  evident  that  powerful  warplanes  af- 
ford the  needed  combination  of  power  and  mobility  in  a 
higher  degree  than  do  any  other  appliances,  and  that 
the  recent  occupation  of  the  Baltic  Islands  by  Germans 
and  the  Italian  reverses  in  the  province  of  Venetia 
could  have  been  prevented  if  the  Allies  had  been  able 
to  send  a  sufficient  number  of  torpedoplanes  and  bomb- 
dropping  aeroplanes  to  assist  the  Russians  and  Ital- 
ians at  the  first  evidence  of  danger ;  and 

Whereas,  It  is  generally  accepted  by  the  recognized 
authorities  on  aeronautics  that  aeroplanes  can  easily 
be  built  which  can  fly  across  the  Atlantic  and  thereby 
solve  the  problem  of  delivering  large  units  of  aero- 
nautic power  to  England,  France,  Italy  and  Russia, 
without  dependence  on  ocean  transportation,  or  inter- 
fering with  it ;  and 

Whereas,  There  are  in  the  United  States  unutilized 
manufacturing  facilities  and  resources  which  could 
build  thousands  of  powerful  warplanes  during  the  com- 
ing year  without  interfering  with  the  present  aero- 
nautical program  of  the  Army  and  Navy;  and 

Whereas,  These  aeroplanes  can  conduct  major 
aerial  operations  against  the  German  fleet  and  U-boat 
bases,  as  well  as  against  the  German  lines  of  communi- 
cation and  military  industries  and  forces;  be  it 

Resolved,  That  these  facts  be  brought  to  the  atten- 
tion of  the  President,  the  Council  of  National  Defense, 
the  Secretary  of  War,  the  Secretary  of  the  Navy,  the 
Aircraft  Production  Board,  and  to  the  American  pub- 
lic, through  the  press,  and  that  the  coming  Congress  be 
urged  to  expand  the  present  aeronautical  program  by 
appropriating  not  less  than  $1,000,000,000  for  build- 
ing an  "Emergency  Air  Fleet"  of  huge  warplanes,  and 


also  appropriate  $1,000,000,000  to  carry  out  a  com- 
prehensive aeronautic  program  of  training  aviators 
and  building  the  tens  of  thousands  of  fighting,  photog- 
raphy, artillery  and  contract  patrol  aeroplanes  ;  dirig- 
ibles and  balloons,  which  are  needed  to  assure  the 
Allies'  supremacy  in  the  air. 

The  $1,032,294,260  Army  Air  Program 

In  December,  1917,  were  made  public  the 
Signal  Corps  estimates  for  1919,  in  which  was 
asked  the  sum  of  $1,032,294,260  for  aeronau- 
tics, including  the  following  items : 


Lighter-than-air  equipment    

Aeroplanes  and  seaplanes    

Spare  parts  and  accessories  

Extra  engines  and  spare  parts  . . 

Maintenance,  upkeep,  and  opera- 
tion of  aero  squadrons  

Aero  stations,  United  States     .  . . 

Aero  stations,  Panama    

Aero  stations,  Hawaii     

Maintenance,  repair,  etc.,  build- 
ings in   Europe    

Purchase  of  land    

Warehouse  and  su])ply  depots   . . 

Aviation  clothing  equipment   .... 

Expenses  of  officers,  enlisted  men, 
and  civilians  on  special  duty  .  . 

Vocational    training    

Mileage  to  officers  and  traveling 
exjienses  of  civilian  employees 

Development  of  new  types  of 
aeroplanes  and  engines   

Schools  of  military  aeronautics  .  . 

Machine-guns   for  aero])lanes    . .  . 

Photographic  equipment,  mate- 
rial, etc 

Contingent  expenses,  office  equip- 
ment,  etc 

Construction    

Leasing  of  land   

Reserve  officers  and  men   

Anemometers,  barographs,  avia- 
tors' garments  and  other  spe- 
cial accessories   

Miscellaneous     


$8,171,000.00 
235,866,000.00 

47,173,200.00 
553,289,120.00 

20,950,000.00 

20,400,000.00 

5,420,000.00 

4,420,000.00 

9,127,000.00 

16,700,000.00 

5,595,000.00 

1,358,440.00 

67,200.00 
120,000.00 

3,050,000.00 

2,000,000.00 

8,050,000.00 

77,475,000.00 

3,405,500.00 

100,000.00 


$279,388.27 

6,240,634.55 

752,930.96 

1367,110.95 

1,249,120.62 


70,462.39 


3,061,293.77 

77,512.13 

400,000.00 


2,841.45 
358,314.90 


Total   aviation    $1,032,294,260.00  $14,159,351.89 

PAY  OF  OKFICKRS  AXD  MEN' 

Pay  of  11,941  officers  $27,619,533.00 

Aviation   increase,  officers    ;    10,030,800.00 

Additional  pay  for  length  of  service,  oflBcers  ....  1 00,000.00 

Pay  of  153,94.5  enlisted  men   60,606,607.05 

Aviation  increase,  men    4,916,800.00 

Additional  pay  for  length  of  service,  men 150,000.00 


Total     $103,423,740.05 

Long  Delay  in   Extending  Plans  and 
Getting  Appropriations  Causes  Trouble 

It  was  most  unfortunate  that  the  necessity  of 
extending  the  aeronautic  program  was  not  rec- 
ognized and  steps  were  not  taken  to  extend  the 
program  in  the  autumn  of  1917. 


220 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


In  official  statements  dated  September  13  and 
31,  Secretaiy  of  War  Xewtoti  D.  Baker  an- 
nounced the  creation  of  the  Liberty  Motor  and 
the  passing  of  its  "final  tests."  On  February 
21, 1918,  he  announced  that  the  first  "American- 
built  battleplanes"  were  en  route  for  France. 

In  March  and  April,  1918,  it  was  made  pub- 
lic that  the  aircraft  program  was  late  by  several 
months. 

The  following  letter,  written  by  Mr.  Alan  R. 
Hawley,  president  of  the  Aero  Club  of  Amer- 
ica, to  President  Wilson,  on  April  2,  1918,  gives 
the  status  of  the  situation  at  the  time,  and  the 
recommendations  made  to  solve  the  problems: 

Mif  dear  Mr.  President: 

A  niimlHT  of  men  who  had  applied  for  admission  in  the  Air 
Service  of  the  Army  have  advised  tlie  Aero  Cluh  of  America  that 
they  have  Iwen  notified  hy  the  Signal  Corps  autlioritics  that  no 
further  enlistments   are   heinp   accepted   at   this   time. 

As  Secretary  Baker's  rejwrt,  published  recently,  stated  there 
were  less  than  four  thousand  aviators  under  training,  and  know- 
ing that  it  will  take  twenty  thousand  aviators  to  keep  five  thou- 
s»nil  aviators  on  the  fighting  front  continuously  for  one  year, 
and  realizing  that  to  lack  the  trained  aviators  to  supply  the 
necessary  replacements  would  mean  defeat  for  the  cause  of  the 
Allies,  we  were  amazed  to  find  this  condition. 

In  answer  to  our  inquiries,  we  were  advised  that  the  reason  no 
further  enlistments  arc  accepted  for  the  Air  Service  is  that  there 
is  a  lack  of  training  fields  and  of  aeronautic  equipment  and  that 
these  cannot  he  provided  heeause  there  are  no  funds  available 
for  the  extension  of  the  Air  Service. 

This  is  only  one  of  the  evidences  that  the  aircraft  program  is 
slowing  down  l>e<"ause  of  lack  of  funds.  We  have  been  advised 
by  factories  that  have  completed  their  orders  that  they  also  do 
not  have  orders  to  look  forward  to  and  to  prepare. 

We  submit,  Mr.  President,  Ihat  this  is  a  mournful  condition 
which  threatens  the  cause  of  tlie  .\llies  more  seriously  tlian  any- 
thing else.  Supremacy  in  the  air  is  to  be  the  key  to  victory.  To 
achieve  and  maintain  supremacy  in  the  air,  the  Allies  must  be 
able  to  count  on  not  less  than  twenty-five  thousand  American 
aviators,  .so  as  to  insure  keeping  five  thousand  at  the  front  con- 
tinuously for  the  various  duties  of  the  Air  Service  and  for  the 
iHimliing  expeditions. 

Tlie  [H-rcenlage  of  replacements  needed  in  the  Air  Service  has 
increased  greatly  in  the  past  six  months  and  will  further  in- 
crea.s*'  in  tlie  coming  year,  becau.se  there  is  mii<-h  more  aerial 
fighting,  attacking  troops  from  the  air,  bomliing  at  low  altitudes 
.ind  night  raiding.  Aerial  fighting  is  becoming  more  and  more 
intense;  and  the  anti-aircraft  guns  are  firing  more  and  more 
accurately  anil  hitting  aeroplanes  at  altitudes  of  sixteen  thou- 
sand feet.  This  increases  the  casualties  among  aviators  enor- 
mously. 

Thiii  condition  to-day  is  analogous  to  the  condition  which 
exi>le<l  last  ()<'tol>er  in  the  American  aircraft  situatiim  as  a 
wlwlc.  A  largi-  numU-r  of  training  camps  had  b«vn  estalilished, 
at  a  cost  of  i^«K),(KK»,(KH),  orders  for  aeroplanes  and  motors  had 
l)c«-n  placed,  and  the  funds  had  practically  been  exhausted. 
Tliereu|Mm  the  work  of  developing  additional  sources  of  sui)plies 
for  aircraft  and  motors  practically  slopped,  notwithstanding  the 
fact  Ihat  the  Italian  reverses  and  the  Uussian  collapse  demanded 
lni|>rrafively  Unit  our  program  Iw  tripled  in  siw. 

TIm'  Aero  Cluh  of  America  officials  urged  aiul  pleaded  for 
prompt  omsiderntion  of  this  new  condition  at  the  time,  and 
pointed  out  that  It  was  aiisolutely  necessary  to  immediately  give 
two  l>ill)4>n  dollars  addilioiinl  a])propriations  for  extending  the 
aircraft    program.    That    wa«    f>ix    inontliii    ago,    when    prompt 


action  would  have  prevented  the  confusion  and  mistakes  which 
were  subsequently  made,  partly  owing  to  lack  of  sufficient  ap- 
propriations. 

Tlie  main  cau.se  of  tlie  present  deploralile  condition  of  our 
aircraft  program  was  that  tlie  authorities  in  charge  tried  to 
make  twenty  thousand  aeroplanes  do  the  work  of  eighty  thou- 
sand. The  original  program  did  not  take  into  consideration 
that  it  takes  an  average  of  two  aeroplanes  to  give  an  aviator 
the  one  hundred  hours  of  preliminary  and  advanced  training 
needed  to  make  him  fit  for  the  present-day  highly  specialized 
work  of  a  military  aviator.  Xor  did  it  take  into  consideration 
that  it  takes  close  to  one  hundred  per  cent,  replacements  per 
month  in  aeroplanes  and  motors  to  keep  aviators  equipped  for 
fighting.  Xor  did  it  take  into  consideration  that  it  takes  forty 
per  cent,  replacements  in  aviators  per  month  to  keep  up  the 
fighting  personnel  of  aero  squadrons. 

In  making  this  program  the  fact  was  overlooked  that  if  the 
plan  was  to  keep  five  thousand  American  aviators  at  the  front, 
it  was  necessary  to  train  twenty-five  thousand.  Therefore,  there 
would  be  required  fifty  thousand  preliminary  and  advanced  train- 
ing aeroplanes  with  which  to  train  them  speedily.  The  number 
of  aeroi)Ianes  under  construction  to-day  is  not  sufficient  to  even 
give  the  preliminary  and  advanced  training  to  the  number  of 
aviators  the  I'nited  States  must  supply  within  the  coming  twelve 
months. 

There  was  also  overlooked  the  fact  that  to  keep  five  thousand 
aviators  equipped  for  action,  there  would  be  required  an  average 
of  two  thousand  aeroplanes  of  different  types  per  month,  or  a 
total  of  twenty-four  tlioiisand  machines  of  different  types  during 
the  twelve  months. 

Having  overlooked  these  very  important  considerations,  the 
authorities  could  not  undertake  to  supply  all  the  aeroplanes 
needed  out  of  the  twenty-two  thousand  planned.  The  Italian 
and  Russian  reverses  created  imperative  needs,  and  the  authori- 
ties received  caliles  requesting  thousands  of  aeroplanes  of  dif- 
ferent types,  l^acking  the  funds  necessary  to  place  additional 
ortlers,  the  authorities  changed  the  orders  of  aeroplanes  under 
construction,  so  as  to  meet  the  requests  from  France.  As  the 
requests  from  France  and  the  suggestions  from  the  different 
Allies  were  for  different  types  of  machines,  the  authorities  kept 
on  changing  the  orders,  so  as  to  supply  these  machines  for  which 
there  seemed  to  be  the  most  pressing  need.  This  led  to  the 
continuous  changes  which  caused  the  set-backs  which  have  re- 
sulted in  the  aircraft  program — which  is  still  the  same  program 
made  at  the  time  when  Italy  was  victorious  and  Russia  was 
still  fighting — being  behind  by  several  months. 

Mad  the  authorities  been  in  a  position  to  place  additional 
orders  whenever  they  received  cables  asking  for  a  given  num- 
ber of  machines  of  a  given  type,  instead  of  having  to  change 
orders  for  machines  under  construction,  to-day  the  original  pro- 
gram would  be  nearly  delivered  and  an  additional  program 
would  be  well  under  way. 

To-day  we  are  making  the  same  mistake  that  was  made  then. 
We  are  stopping  the  enlisting  of  aviators  and  no  .steps  have  lieen 
taken  to  extend  the  program  to  meet  the  new  conditions  which 
have  arisen,  and  which,  unless  they  are  met  ])r(nnptly,  may  result 
in  Allied  reverses  and  )>ublic  condemnation  of  your  .Vdministra- 
tion,  not  only  from  the  .\niericaii  pulilic  liut  also  from  the  Allies. 

It  is  tragic  to  us,  .Mr.  President,  to  know  that  while  aeroplanes 
and  aviators  are  needed  so  badly  to  fight  this  figlit  lor  civiliza- 
tion and  humanity,  hundreds  of  manufacturers  who  could  lie 
making  aeroplanes  and  motor  parts  are  kept  in  forced  idleness 
for  lack  of  orders,  and  thousands  of  patriotic  young  men  who 
are  anxious  to  join  the  Air  Service  and  go  to  France  and  do 
their  share  towards  winning  the  war,  are  told  that  no  further 
men  are  lieing  taken  in  the  Air  Services. 

The  delay  in  ])rodiicing  the  I.ilierty  motor  cannot  be  held  re- 
sp<msible  for  not  giving  preliminary  and  advanced  training  to 
aviators.  This  training,  which  includes  cross-country  Hying, 
boml)-drop])lng,  shooting  at  moving  targets  from  aeroplanes, 
could  be  given  with  existing  types  of  machines  ami  motors. 

We  submit,  .Mr.  President,  that  action  must  be  taken  pronqitly. 

We  agree  with  the  memliers  of  Congress  who  advise  us  that 
those  in  charge  of  the  present  aircraft  program  have  failed  to 
make  good  and  that  it  is  hardly  possible  to  expect  better  from 


HISTORY  OF  UNITED  STATES  ARMY  AERONAUTICS 


221 


the  same  organization  if  conducted  hy  the  same  authorities  on 
the  ))resent  plan  of  action. 

W'c  liave  lollowod  tlie  aircraft  program  step  by  step  and  are 
familiar  witli  tlic  inside  prol)lems  tliat  liave  caused  the  delays. 
TIk'sc  causes  are  numerous,  l)ul  the  main  ones  arc: 

(I)  Lacl<  of  concentrated  rcsponsihility,  authority  and  con- 
trol in  the  management  of  aerial  matters. 

{'2)  Lack  of  sufficient  ai)proi)riations  to  extend  tiie  aircraft 
program  to  meet  the  military  needs  of  the  Allies; 

(;i)  Lack  of  touch  between  the  authorities  dealing  with  the 
strategic  side  o*'  the  war  and  the  authorities  iiaving  charge  of  the 
supplying  of  aircraft  and  aviators  needed  to  build  American 
and  Allied  air  forces. 

(4)  The  lack  of  a  Government  department  having  the  au- 
thority and  organization  necessary  to  deal  with  all  aircraft  mat- 
ters and  ])revent  delays  due  to  division  of  res])onsil)ility,  bu- 
reaucratic jealousies  and  officials  over  matters  of  departmental 
jurisdiction,  duplication  of  efforts,  etc.  Tlie  present  Aircraft 
Board  is  only  an  advisory  board  an<l  has  no  jiowcr  to  act  or  to 
get  the  necessary  organization  to  extend  or  carry  out  an  ex- 
tended aircraft  program. 

To  correct  the  situation,  two  successive  steps  must  be  taken, 
as   follows : 

(1)  The  immediate  appointment  of  an  Assistant  Secretary  of 
War  and  an  Assistant  Secretary  of  the  Navy  to  represent  the 
Army  and  Xavy,  respectively,  in  the  Aircraft  Board.  This  is 
to  solve  the  immediate  problems  while  the  second  step  is  being 
taken. 

(2)  The  creation  of  a  Department  of  Aeronautics,  ba.sed  on 
the  British  plan,  which  i)laces  the  Air  Services  under  a  separate 
Department  of  Aeronautics,  the  head  of  which  is  independent  of, 
although  cooperating  closely  with,  the  War  and  Xavy  De- 
])artincnts. 

The  British  Uovernment  went  through  every  one  of  the  trou- 
bles we  have  gone  through  in  connection  with  our  air  service. 
The  official  reports  of  the  investigation  of  the  British  Air  Service 
in  191()  shows  that  there  were  scandals  and  charges,  counter- 
charges and  confusion,  just  as  we  have  in  the  United  States  to- 
day. After  three  years  of  trying  different  plan.s,  the  military 
and  naval  authorities  and  other  branches  of  the  British  Govern- 
iiieiit  came  to  the  conclusion  that  the  only  solution  was  a  .se])a- 
rale  Department  of  Aeronautics,  with  an  Air  Minister  at  the 
head,  whose  functions  are  identical  with  the  duties  of  the  War 
Minister  and  the  First  Lord  of  the  Admiralty. 

A  separate  Department  of  Aeronautics  is  the  only  solution  to 
all  the  problems  of  building  the  air  forces  needed  to  win  the  war. 

We  must  add  that  many  of  tVie  officials  in  charge  of  the  air- 
craft program  and  the  members  of  their  staffs  arc  able  men 
who,  if  placed  in  a  Department  of  Aeronautics  and  given  the 
power  necessary  to  act  and  to  get  together  an  efficient  organiza- 
tion, and  the  necessary  funds,  will  quickly  save  the  situation  and 
enable  the  United  States  to  do  its  share  in  the  air  this  year. 

It  is  well  to  add  that  an  important  consideration  that  led  to 
the  creation  of  the  Air  Ministry  in  Great  Britain  was  the  knowl- 
edge that  Germany  is  planning  extensive  aerial  mail,  express  and 


passenger  transportation  lines,  to  employ  the  output  of  her  air- 
craft factories  after  the  war.  Germany's  plans  are  extensive 
enough  to  employ  tens  of  thousands  of  aircraft.  This  would 
give  her  a  reserve  air  fleet  large  enough  to  blow  England,  France 
or  Italy  off  the  map  overnight. 

As  was  brought  out  in  the  House  of  Commons  by  Lord  Mon- 
tague, aircraft  can  be  turned  from  vehicles  of  transportation  to 
war  machines  by  the  simple  process  of  substituting  bombs  as 
cargo.  Any  nation  that  overlooks  this  fact  may  pay  dearly  for 
it  overnight. 

We  all  ho|)e,  of  course,  that  some  agreement  may  be  reached 
between  the  nations  which  will  guarantee  against  such  a  horror, 
as  the  liombing  of  a  nation  out  of  existence  overnight  by  another 
nation  having  tens  of  thousands  of  aeroplanes.  But  the  i)resent 
war  has  shown  that  hopes  do  not  save  nations  from  the  outrages 
of  aggressors.  y\s  a  matter  of  fact,  Germany's  first  air  raids 
of  Great  Britain  were  conducted  by  Zeppelins,  which  were  em- 
])loyed  for  ])assenger  carrying  before  the  war.  So,  while  keeping 
our  hearts  in  the  right  place,  we  must  be  ready  to  i)rotect  the 
Republic  and  the  rights  of  Humanity  and  the  Cause  of  Civiliza- 
tion. To  do  this  will  require  direct  control  and  supervision  of 
military  and  commercial  air  fleets,  and  this  can  only  be  done  by 
a  well  organized   Department  of  Aeronautics. 

In  conclusion  may  we  point  out  that  in  the  past,  events  have 
always  proven  that  our  suggestions,  which  were  terme<l  as  ex- 
cessive by  some  people  at  the  time  they  were  made,  were  most 
conservative.  We  beg  you  to  judge  these  recommendations  ac- 
cordingly. 

Assuring  you  of  the  hearty  cooperation  of  the  Aero  Club  of 
America  and  its  affiliated  Aero  Clubs  and  cooperating  organiza- 
tions, 1  beg  to  remain 

Very  trul'-  yours, 

(Signed)    Aiax    R.   Hawley, 
President,  Aero  Club  of  America. 

Following  a  report  on  the  aircraft  situation 
made  to  President  Wilson  by  G.  Borglum,  on 
March  12  the  War  Department  announced  the 
appointment  of  a  committee  on  Aircraft  Inves- 
tigation, consisting  of  H.  Snowden  Marshall, 
Edward  Wells,  and  Gavin  McNab.  This  com- 
mittee reported  its  findings  to  President  Wilson 
in  April.  In  the  meantime  the  Senate  Com- 
mittee on  Military  Affairs  investigated  the  air- 
craft situation  and  reported  on  April  10.  This 
report  was  printed  in  full  in  "Flying,"  for  May, 
1918. 


Memoranda: 


The  first  flight,  December  17,  lOO;?.  Orville  Wrisht  at  the  helm;  \Vilber  Wrifrlit  alDiijrside  of  machine.  Date,  December  17, 
1903.  Time,  10:30  a.m.,  U:00  m.  First  flipht,  twelve  seconds.  Longest  flight,  fifty-nine  seconds.  Wind  velocity,  twenty  to  twen- 
ty-five miles  per  hour.  Weight  of  machine,  ()05  pounds.  Total  weight,  with  operator,  750  pounds.  Power  of  motor,  ten  to  twelve 
horsepower.  Weight  carried  per  horsepower,  sixty-three  pounds.  Speed  of  motor  in  flight,  1030  r.p.m.  Speed  of  propeller,  3M) 
r.p.m.  Spread  of  wings,  forty  feet,  four  inches.  Ix'ngth  of  chord,  six  feet,  six  inches.  Total  area  of  wings,  530  square  feet. 
Area  of  elevator  forty-eight  square  feet.    Area  of  vertical  rudder,  twenty  square  feet. 


CHAPTER  XVIII 
THE  EVOLUTION  OF  MILITARY  AVIATION 


As  a  matter  of  history,  the  first  aeroplane 
actually  ordered  by  and  constructed  i'or  a  gov- 
ernment was  designed  and  built  by  Clement 
Ader,  the  French  pioneer,  in  1890-97.  ^Nlon- 
sieur  Ader,  an  electrical  engineer  by  profession, 
was  an  intense  patriot,  and  after  taking  part  in 
the  Franco-Prussian  War  of  1870,  thought 
France  could  have  been  saved  from  disaster  by 
an  air  fleet.  Thereupon  he  set  himself  to  study 
the  flight  of  birds,  and  having  found  an  Indian 
bat  that  .seemed  easy  to  imitate,  constructed  a 
large  bat-like  craft,  which  he  fitted  with  a  40 
horse-power  steam  motor  and  two  propellers. 
At  the  first  trial  in  1890,  this  machine,  driven  by 
its  own  propellers,  is  said  to  have  left  the  ground 
in  a  jump.  The  French  Government  consid- 
ered the  craft  of  value,  and  engaged  Ader  on  a 
program  which  included  nothing  less  than  the 
founding  of  an  arsenal  for  the  construction  of 
flying  machines,  the  establi.shment  of  an  aviation 
sch(K)l,  and  the  creation  of  an  aerial  fleet.  For 
this  purpose  a  first  appropriation  of  $100,000 
was  made. 

The  expectation  proved  disastrous  to  Ader, 
for  when  he  finished  the  first  machine  in  1897, 


after  six  years  of  hard  work,  it  did  not  fly  and  the 
authorities  refused  to  further  finance  the  enter- 
prise. 

Subsequently,  in  1905-06,  the  French  Gov- 
ernment negotiated  with  the  Wright  brothers 
for  the  acquisition  of  their  machine,  but  imposed 
a  condition  that  it  should  be  guaranteed  to  reach 
a  height  of  3000  feet.  This  was  later  modified 
to  1000  feet.  The  Wright  brothers,  with  their 
usual  caution,  replied  that  they  had  never  flown 
higher  than  100  feet,  and  rather  than  promise 
what  they  did  not  care  to  prove,  they  let  the  ne- 
gotiations drop.  The  demand  it.self  shows  that 
it  was  not  suggested  by  actual  knowledge  of 
aeroplanes,  but  deduced  from  performances  of 
balloons  and  dirigibles. 

At  about  the  time  of  Ader's  experiment  the 
British  Government  became  interested  enough 
to  finance  the  experiment  of  Sir  Hiram  Maxim 
in  FiUgland.  This  inventor  constructed  a  large 
aircraft  of  the  multiplane  type,  120  feet  from 
tip  to  tip,  fitted  with  two  steam-engines  of 
175  horse-j)ower  capacity,  and  weighing  7000 
pounds.  I>ike  Ader's  experiment,  it  was 
wrecked  in  the  attempt  to  fly  it,  and  the  military 


222 


THE  EVOLUTION  OP^  MILITARY  AVIATION 


223 


authorities,  who  had  been  expecting  to  get  a 
practical  craft  out  of  the  first  experiment,  were 
disappointed  and  withdrew  their  support. 

In  1908  the  Board  of  Ordnance  and  Fortifi- 
cations of  tlie  United  States  Army  directed 
Samuel  P.  Langley  to  construct  a  large-sized 
model  of  the  "aerodrome"  he  had  designed,  and 
made  an  aj)propriation  of  $.30,000  to  defray  the 
cost  of  the  experiment.  Langley's  machine 
was  a  tandem  monoplane,  48  feet  from  tip  to 
tip  and  52  feet  from  bowsprit  to  the  end  of  its 
tail.  It  was  fitted  with  a  .50  horse-power  en- 
gine and  weighed  830  pounds.  Two  attempts 
to  launch  it  were  made,  one  on  October  7  and 
the  other  on  December  8,  1903.  On  both  occa- 
sions, according  to  reports,  the  "aerodrome"  be- 
came entangled  in  the  defective  launching  ap- 
paratus and  was  thrown  headlong  into  the  Po- 
tomac River,  on  which  the  launching  trials  were 
made.  Following  the  last  failure,  when  the 
"aerodrome"  was  wrecked,  the  press  ridiculed 
the  whole  enterprise,  and  Congress  refused  to 
appropriate  money  for  further  experiments. 

The  first  requisition  for  a  military  aeroplane, 
giving  definite  specifications  of  what  the  aero- 
plane should  accomplish  to  be  acceptable  for 
military  service,  was  made  by  the  United  States 
War  Department  in  an  advertisement  issued 
December,  1907.  This  advertisement  is  a  won- 
derful document.  It  exacted  the  utmost,  with- 
out going  into  the  impossible.  It  shows  that 
at  that  time — when  Bleriot,  Farman,  and  Cur- 
tiss  had  only  made  a  few  jumps,  and  the  per- 
formances of  the  Wrights  had  not  been  made 
public — the  authorities  at  Washington  had  a 
thorough  knowledge  of  the  aeroplane  and  a 
lucid  conception  of  its  possibilities.  The  full 
text  of  the  advertisement  is  reproduced  herewith 
for  its  historical  value: 

Signal  Corps  Specification,  No.  486 

ADVERTISEMENTS  AND  SPECIFICATION  FOR  A 
A  HEAVIER-THAN-AIR  FLYING  MACHINE 

To  the  pub  ic: 

Sealed   proposals,   in   duplicate,  will  be  re- 

"  ceived  at  this  office  until  12  o'clock  noon  on 

February  1,  1908,  on  behalf  of  the  Board  of 

Ordnance  and  Fortification  for  furnishing  the 


Signal  Corps  with  a  heavier-than-air  flying  ma- 
chine. All  proposals  received  will  be  turned 
over  to  the  Board  of  Ordnance  and  Fortifica- 
tion at  its  first  meeting  after  February  1  for  its 
official  action. 

Persons  wishing  to  submit  proposals  under 
this  specification  can  obtain  the  necessary  forms 
and  envelopes  by  application  to  the  Chief  Signal 
Officer,  United  States  Army,  War  Depart- 
ment, Washington,  D.  C.  The  United  States 
reserves  the  right  to  reject  any  and  all  pro- 
posals. 

Unless  the  bidders  are  also  the  manufacturers 
of  the  flymg  machine,  they  must  state  the  name 
and  place  of  the  maker. 

Preliminary. — This  specification  covers  the 
construction  of  a  flying  machine  supported  en- 
tirely by  the  dynamic  reaction  of  the  atmos- 
phere and  having  no  gas  bag. 

Acceptance. — The  flying  machine  will  be  ac- 
cepted only  after  a  successful  trial  flight,  dur- 
ing which  it  will  comply  with  all  requirements 
of  this  specification.  No  payments  on  account 
will  be  made  until  after  the  trial  flight  and 
acceptance. 

Inspection.— The  Government  reserves  the 
right  to  inspect  any  and  all  processes  of  manu- 
facture. 

GENERAL   REQUIREMENTS 

The  general  dimensions  of  the  flying  ma- 
chine will  be  determined  by  the  manufacturer, 
subject  to  the  following  conditions: 

1.  Bidders  must  submit  with  their  proposals 
the  following:  (a)  Drawings  to  scale  show- 
ing the  general  dimensions  and  shape  of  the  fly- 
ing machine  which  they  propose  to  build  under 
this  specification,  (b)  Statement  of  the  speed 
for  which  it  is  designed,  (c)  Statement  of  the 
total  surface  area  of  the  supporting  planes. 
(d)  Statement  of  the  total  weight,  (e)  De- 
scription of  the  engine  which  will  be  used  for 
motive  power,  (f)  The  material  of  which  the 
frame,  planes,  and  propellers  will  be  con- 
structed. Plans  received  will  not  be  shown  to 
other  bidders. 

2.  It  is  desirable  that  the  flying  machine 
should  be  designed  so  that  it  may  be  quickly  and 
easily  assembled,  and  taken  apart  and  packed 


224  TEXTBOOK  OF  MILITARY  AERONAUTICS 

for  transportation  in  army  wagons.  It  should  will  be  required  of  at  least  one  hour,  during 
be  capable  of  being  asseml)led  and  put  in  opera-  which  time  the  flying  machine  must  remain  con- 
ting  condition  in  al)out  one  hour.  tinuously  in  the  air  without  landing.     It  shall 

3.  The  flying  machine  must  be  designed  to  return  to  the  starting  point  and  land  without 
carry  two  persons  having  a  combined  weight  of  any  damage  that  would  prevent  it  immediately 
about  S.'iO  pounds,  also  sufficient  fuel  for  a  flight  starting  upon  another  flight.  During  this  trial 
of  12.)  miles.  flight  of  one  hour  it  must  be  steered  in  all  direc- 

4.  The  flying  machine  should  be  designed  to  tions  without  difficulty,  and  must  be  at  all 
have  a  speed  of  at  least  40  miles  pei-  hour  in  still  times  under  perfect  control  and  equihbrium. 
air,  but  bidders  must  submit  quotations  in  their  7.  Three  trials  will  be  allowed  for  speed  as 
proposals  for  cost  depending  upon  the  speed  at-  provided  for  in  paragraphs  4  and  5.  Three 
tained  during  the  trial  flight,  according  to  the  trials  will  be  for  endurance,  as  provided  for  in 
following  scale:  paragraph  6,  and  both  tests  must  be  completed 

40  miles  per  hour    100  per  cent.  ^'t.^^'"  ^  P^;""^  "f  thirty  days  from  the  date  of 

39  miles  per  hour    90  per  cent.  delivery.     The  expcnsc  of  the  tests  is  to  be  borne 

S  S: ;::;  iZ  ;:::::;;::;:::::::::;  ;?o  i:::  Zl  ^y  t'^e  manufacturer.  The  place  of  delivery  to 

36  miles  per  hour 60  per  cent.  the  (iovemmcnt  and  trial  flights  will  be  at  Fort 

Less  than  36  miles  per  hour  rejected.  JMver    Virj>"inin 

41  miles  per  hour     110  per  cent.  o      Ti     i         i  i  l              i       • 

*2  miles  i>er  hour     1:.>0  i.er  cent.  »•    At  Shouid  DC  SO  dCSlgUCd  aS  tO  aSCCud  lU  any 

43  miles  p<-r  hour    130  per  cent.  countrv  which  may  be  encountered  in  Held  serv- 

44  nnles  per  hour     140  per  cent.  .               *                      . 

ice.     I  he  starting  device  must  be  simple  and 

5.  The  speed  accomplished  during  the  trial  transportable.  It  should  also  land  in  a  field 
flight  will  be  determined  by  taking  an  average  without  requiring  a  specially  prepared  spot  and 
of  the  time  over  a  measured  course  of  more  than  without  damaging  its  structure. 

five  miles,  against  and  with  the  wind.     The  time  9.  It  should  be  provided  with  some  device  to 

will  be  taken  by  a  flying  start,  passing  the  start-  permit  of  a  safe  descent  in  case  of  an  accident  to 

ing  point  at  full  speed  at  both  ends  of  the  course,  the  propelling  machinery. 

This  test  is  subject  to  such  additional  details  as  10.  It  should  be  sufficiently  simple  in  its  con- 

the  Chief  Signal  Officer  of  the  army  may  pre-  struction  and  operation  to  permit  an  intelligent 

scribe  at  the  time.  man  to  become  proficient  in  its  use  within  a  rea- 

6.  Before  acceptance  a  trial  endurance  flight  sonable  length  of  time. 


Next  the  British  Government  engaged  Sir  Hiram  Maxim  to  bulla   :i   mllil.ii)    a. mpLiiK.     Sir    .Maxun's  multipldnc   ul>o  <  auic   to 

grief  In  an  attempt  to  show  its  flying  qualities. 


THE  EVOLUTION  OF  MILITARY  AVIATION 


225 


11.  Bidders  must  furnish  evidence  that  the 
Government  of  the  United  States  has  the  lawful 
right  to  use  all  patented  devices  or  appur- 
tenances which  may  be  part  of  the  flying  ma- 
chine, and  that  the  manufacturers  of  the  flying 
machine  are  authorized  to  convey  the  same  to  the 
Government.  This  refers  to  the  unrestricted 
right  to  use  the  flying  machine  sold  to  the  Gov- 
ernment, hut  does  not  contemplate  the  exclusive 
purchase  of  patent  rights  for  duplicating  the 
flying  machine. 

12.  Bidders  will  be  required  to  furnish  with 
their  proposal  a  certified  check  amounting  to 
ten  per  cent,  of  the  price  stated  for  the  40-mile 
speed.  LTpon  making  the  award  for  this  flying 
machine,  these  certified  checks  will  be  returned 
to  the  bidders,  and  the  successful  bidder  will  be 
required  to  furnish  a  bond,  according  to  army 
regulations,  of  the  amount  equal  to  the  price 
stated  for  the  40-mile  speed. 

13.  The  price  quoted  in  proposals  must  be 
understood  to  include  the  instruction  of  two 
men  in  the  handling  and  operation  of  this  flying 
machine.  No  extra  charge  for  this  service  will 
be  allowed. 

14.  Bidders  must  state  the  time  which  will  be 
required  for  delivery  after  receipt  of  order. 

James  Aixen, 
Brigadier-General,  Chief  of  Signal  Officer  of 
the  Army. 

Signal  Office, 

Washington,  D.  C,  December  23,  1907. 

The  Wright  brothers  were  the  only  persons  to 
submit  a  complete  machine  and  fulfil  the  require- 
ments. The  first  trials,  made  by  Orville 
Wright  at  Fort  Myer  in  September,  1908,  re- 
sulted in  a  record  flight  of  1  hour,  14  minutes, 
20  seconds.  An  accident  prevented  the  fulfil- 
ment of  the  passenger-carrying  requirement  and 
caused  a  delay  of  one  year. 

The  Wright  machine,  which  fulfilled  the  con- 
ditions in  August,  1909,  was  the  old-type 
Wright  biplane.  It  had  a  spread  of  40  feet,  a 
25  horse-power  motor,  front  elevator,  skids  in- 
stead of  wheels,  and  was  started  by  catapult  and 
monorail.  The  record  flights  made  during  the 
tests  at  Fort  Myer  included  a  flight  of  1  hour, 
20  minutes,  30  seconds,  and  one  of  1  hour,  28 


minutes,  20  seconds,  with  Lieutenant  Frank  P. 
Lahm  as  passenger. 

It  was  most  appropriate  that  the  distinction 
of  supplying  the  first  aeroplane  to  the  United 
States  Government  should  have  gone  to  the 
Wrights,  who  gave  the  world  the  first  practical 
aeroplane.  Wilbur  Wright  and  his  brother, 
Orville  Wright,  two  men  of  remarkable  char- 
acteristics, sons  of  the  Rev.  Milton  Wright, 
were  presented  in  their  boyhood,  thirty  odd 
years  ago,  with  a  toy  helicopter,  a  butterfly- 
shaped  contrivance,  consisting  of  paper  wings 
fitted  with  a  tin  propeller  which,  when  made  to 
revolve  by  twisted  rubber,  caused  the  toy  to 
shoot  forward  through  the  air.  That  toy  fired 
their  imagination,  and  they  saw  it,  in  magnified 
form,  capable  of  carrying  a  man. 

Their  attempt  to  fly  large  helicopters  con- 
structed on  the  idea  of  the  toy  did  not  bring 
practical  results,  and  until  1896  they  did  not 
give  the  matter  of  artificial  flight  more  than 
passing  attention.  In  the  summer  of  that  year, 
however,  the  news  of  the  accident  and  death  of 
Otto  Lilienthal,  the  German  champion  of  glid- 
ing flight,  stirred  them  to  action,  and  they  set 
themselves  to  study  aerodjmamics  and  the  works 
of  Lilienthal,  ]\Iouillard,  Chanute,  Maxim  and 
Langley,  the  most  prominent  experimenters  at 
that  time. 

Their  experiments  with  a  glider  began  in  the 
autumn  of  1900  at  Kitty  Hawk,  North  Caro- 
lina. There,  on  the  barren  sand-dunes  of  North 
Carolina,  these  two  intrepid  investigators  took 
all  the  theories  of  flight  and  tried  them  one  by 
one,  only  to  find  after  two  years  of  hard,  dis- 
couraging work,  that  they  were  based  more  or 
less  on  guesswork.  Thereupon  they  cast  aside 
old  theories  and  patiently  put  the  apparatus 
through  innumerable  gliding  tests,  ever  chang- 
ing, adding,  and  modifying.  They  set  down 
the  results  after  each  glide,  comparing  and 
changing  details  again  and  again,  advancing 
inch  by  inch,  until  they  at  last  developed  a  glider 
wonderfully  exact,  which,  when  fitted  with -a 
light  motor  also  built  by  them,  made  initial 
flights  on  December  17,  1903,  of  from  twelve  to 
fifty -nine  seconds'  duration.  This,  then,  was 
the  birth  of  the  aeroplane, — the  flimsy,  icono- 
clastic thing  which  seems  to  evade  Newton's 


226 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


The  first  "gun-plane"  was  the   French   Voisin   armored   and   armed   with  a  37   mill,  gun,  Itbled  early   in    liHi.     It   (li.-.jinnru    iljc 

theory  that  the  recoil  of  a  gun  would  upset  the  aeroplane. 


laws,  eliminates  frontiers,  and  promises  to  ex- 
pand civilization  as  much  as  have  the  steamship, 
the  railway,  and  electricity. 

On  September  15,  1904,  Orville  Wright, 
flying  the  Wright  biplane  near  Dayton,  Ohio, 
made  the  first  turn  in  a  heavier-than-air  ma- 
chine. On  September  20,  he  made  the  first 
circle;  on  October  4,  1905,  he  made  the  first 
flight  of  over  half  an  hour,  a  flight  lasting  33 
minutes,  17  seconds. 

The  Wrights  did  not  make  their  achieve- 
ments public  at  the  time;  in  fact,  until  1908 
they  flew  only  in  private. 

The  report  of  their  wonderful  achievement, 
nevertheless,  spread  far  and  wide.  It  stimu- 
lated those  who  had  given  up  experimenting  and 
inspired  others  to  take  up  experiments.  Octave 
Chanute,  in  1902,  went  to  France  and  related 
the  early  successes  of  the  Wrights  with  their 
glider,  describing  the  general  shape  of  the 
Wright  machine.  The  result  of  this  trip  was 
that  half  a  dozen  enthusiasts,  including  Louis 
Bleriot,  Captain  Louis  Ferber,  Ernest  Arch- 
deacon, and  later  the  Voisin  brothers  and  Al- 
berto Santos-Dumont,  took  up  the  work,  thus 
founding  the  mighty  French  school,  which  has 
increased  so  greatly  and  done  so  much  ever  since. 
The  first  member  of  this  school  to  succeed  was 
Santos-Dumont,  the  Brazilian  aeronaut  sports- 
man. He  constructed  a  machine  of  original 
design,  and  in  1906  made  short  sustained  flights 
of  from  fifty  to  seven  hundred  feet  in  a  straight 
line.     This  created  a  world-wide  sensation  at 


the  time.  Meanwhile,  others  of  the  French 
school  graduated  and  won  honors.  The  Voisin 
brothers  became  constructors  and  teachers,  and 
with  their  cooperation  Leon  Delagrange,  Henry 
Farman,  Louis  Bleriot,  and  others,  prosecuted 
practical  experiments  and  succeeded  in  getting 
their  creations  to  leave  the  ground  for  modest 
flights.  At  this  juncture,  during  the  summer 
of  1908,  the  Wrights  started  to  give  pubhc 
demonstrations.  Their  methods  supplied  and 
suggested  to  the  French  experimenters  the 
means  to  modify  and  improve  their  aeroplanes, 
particularly  the  method  of  balancing  them, 
which  had,  until  then,  been  a  perplexing  prob- 
lem. 

The  conditions  set  by  the  United  States  Gov- 
ment  in  its  specification  of  1907-08  formed  the 
standard  by  which  most  governments  judged 
aeroplanes  acquired  for  military  work  until  the 
close  of  1911,  when  the  French  Military  Com- 
petition took  place.  This  competition  was  or- 
ganized by  the  French  War  Department  at  the 
close  of  1910,  after  the  military  manoeuvers,  with 
a  view  to  develop  better  aeroplanes  for  military 
purposes.  The  conditions  to  be  fulfilled  by  the 
competing  aeroplanes  and  the  prizes  to  be 
awarded  to  the  winners  were  as  follows : 

General  Conditions  of  French  Military 
Competition  of  19101911 

1.  The  aeroplane  and  its  engine  must  have 
been  constructed  in  France  of  the  best  ma- 
terials. 


THE  EVOLUTION  OF  MILITARY  AVIATION 


227 


2.  Each  aeroplane  must  make  a  circular 
flight  of  300  kilometers  (186  miles)  without  a 
stop. 

3.  Each  aeroplane  on  this  circular  flight  must 
carry  a  load  of  300  kilograms  (660  pounds)  over 
and  above  the  requisite  petrol,  oil,  water,  etc. 

4.  JMachines  must  provide  accommodation  for 
three  passengers:  the  pilot,  a  mechanic,  and  an 
observer. 

5.  The  mean  speed  must  be  not  less  than  60 
kilometers  per  hour  (37.3  miles) . 

6.  Machines  must  be  able  to  land  without  dif- 
ficulty or  damage  on  plowed  fields,  meadows, 
stubble,  etc.,  and  must  start  again  from  ground 
of  this  character, 

7.  Machines  must  be  easily  transportable, 
whether  packed  or  not,  by  road  or  rail,  and 
should  be  easily  assembled. 

The  following  hints  were  given  to  construct- 
ors: 

1.  It  is  desirable  that  the  aeroplane  be  fitted 
with  a  double  control;  or,  at  all  events,  that  the 
pilot  and  his  assistant  should  be  able  to  relieve 
one  another  by  taking  over  the  control  in  flight. 

2.  It  is  desirable  that  machines  should  be  ca- 
pable of  starting  without  outside  assistance. 

3.  The  observer's  field  of  vision  should  not  be 
obstructed  by  any  parts  of  the  machine. 


with  their  full  load.  The  final  classification  will 
be  made  according  to  the  best  performance  dur- 
ing this  test. 

PRIZES 

The  prizes  will  be  awarded  as  follows:  The 
machine  accomplishing  the  best  performance 
will  be  bought  by  the  Ministry  of  War  for  the 
sum  of  100,000  francs  and  its  constructor  will  re- 
ceive an  order  for  10  machines  of  a  similar  type 
at  40,000  francs  each.  An  extra  premium  of 
.500  francs  will  be  granted  in  addition  for  each 
kilometer  of  average  speed  above  60  kilometers 
per  hour  that  the  machine  has  attained.  The 
constructors  of  the  machines  accomplishing  the 
second  and  third  best  performances  will  receive 
orders  for  six  and  four  machines  respectively,  at 
the  same  prices.  In  the  case  where  only  two 
machines  come  through  the  tests  satisfactorily, 
the  constructor  of  the  first  will  receive  an  order 
for  twelve  machines  and  the  constructor  of  the 
second  an  order  for  eight  machines ;  and  if  only 
one  machine  has  satisfactorily  passed  the  tests  its 
constructor  will  receive  an  order  for  20  ma- 
chines. 

The  genei'al  conditions  of  this  contest  were 


i';'f4'-l>*ss''' 


-irnm?T^^m 


PRELIMINARY   TESTS 

1.  Three  flights  must  be  made  with  the  above 
stated  load  on  board,  and  a  landing  accom- 
plished on  ground  of  the  nature  indicated  in 
paragraph  6  above.  On  each  occasion  machines 
must  reascend,  start  from  the  ground  and  land 
again  after  a  flight  of  a  few  minutes. 

2.  The  machine  carrying  its  full  load  must 
make  a  flight  over  a  circular  course  for  the  pur- 
pose of  testing  its  speed. 

3.  Two  altitude  flights,  with  the  full  load, 
must  be  made,  during  which  machines  must 
reach  a  height  of  500  meters  (1640  feet)  within 
15  minutes. 

TWO    FINAL   TESTS 

On  a  day  appointed  beforehand  all  the  ma- 
chines that  have  successfully  passed  the  prelimi- 
nary tests  shall  make  a  non-stop  flight  over  a 
circular  course  of  300  kilometers   (186  miles) 


How  they  tried  to  shoot  over  the  propeller  up  to  1915,  before 
the  method  of  synchronl/.inf;  the  gun  with  the  propeller  to  per- 
mit shooting  through  it  was  found,  a  French  improvement. 


228 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


French  Caudron  biplane  equipped  with  two  motors.     (Official  French  photo.) 


over  100  per  cent,  more  severe  and  more  detailed 
than  the  general  conditions  of  the  American 
competition.  The  aeroplane  had  been  tried  in 
the  military  manoeuvers  of  1910,  and  from  its 
accompli-shments  the  authorities  had  deduced  its 
great  possibilities — if  further  developed — to 
give  the  amount  and  quality  of  service  exacted 
as  minimum  in  the  competition.  The  conditions 
show  that  the  authorities  had  a  thorough  knowl- 
edge of  what  an  aeroplane  would  have  to  do  to 
suit  for  general  military  work,  and  the  large 
prizes  offered  show  that  they  were  aware  that  to 
develop  the  required  standard  efficiency  was  to 
involve  lengthy  and  costly  experiments,  which 
few  of  the  constructors  could  carry  out  unless  a 
liberal  inducement  was  given.  As  it  was,  the 
contest  had  to  be  postponed  for  six  months  to 
give  an  opportunity  to  constructors  to  develop 
the  required  qualities. 

Encouraged  by  the  inducements  given,  six- 
teen French  constructors  built  special  aero- 
planes, thirty-four  in  number,  whose  general 
characteristics  were  as  follows: 


Make 


Type 


Span     Length       Motor 


„p    Weight 
^^-      Kilo. 


Antoinette        Monoplane 
Aktra  Biplane 

'■  Triplane 

Antra-Wrlght  Biplane 
Bitriot  Monoplane 


Brtgnet 


Biplane 


Deperduuio     Monoplane 
U.  Karman       Biplane 

M.  Pannan 

OoupT 

Moru>*-Bor«l  Monoplane 


52'    6" 

40' 

43' 

52' 

36' 

36' 

63' 

41'    4" 

41'    4" 

63' 

41'    4" 

53' 

40'    6- 

39'    0" 

40'    G' 

64' 

64' 

62' 10" 

62'  10" 

64' 

64' 

41' 

44' 


36' 

34' 3" 

31' 

34' 

27' 

27' 

20' 

28'  G" 

28'  G" 

29' 

28' 6" 

29' 

80' 

30'  . 

30' 

38' 

82' 6" 

82' 

82' 

87' 8" 

88' 

88' 

83' 


Antoinette 

Chcnu 

Renault 

GnAme 


Dancette 

Canton-Une 
It         <( 

OnOme 
Anzanl 
ClergPt 
Renault 

OnAme 

Renault 

Cbenu 
OoAma 


60 

75 

75 

50 

100 

130 

100 

130 

100 

110 

110 

80 

100 

80 

100 

76 

76 

70 

100 

76 

76 

76 

100 

180 


936 
862 
760 
G24 
4G5 
515 
652 
637 
652 
722 
703 
700 
462 

626 
691 
691 

471 
689.B 

618 
637 


Make 

Type 

Span 

Length 

Motor 

H.P. 

Weight 
Kilo. 

Nieuport 

•• 

41' 

29' 

" 

100 

483 

" 

" 

41' 

29' 

" 

100 

483 

Paulhan 

Triplane 

41' 

6" 

33' 

Renault 

75 

R    E    P. 

Biplane 

30' 

33' 

R.  E.  P. 

60 

Savary 

" 

62' 

38' 

Labor 

70 

708 

" 

«« 

62' 

38' 

" 

70 

708 

Voisin 

<t 

48' 

33' 

GnOme 

130 

622 

*' 

« 

48' 

33' 

Renault 

75 

674 

** 

<f 

48' 

8" 

33' 

" 

75 

674 

Zodiac 

** 

48' 

32' 

" 

75 

674 

The  final  tests  were  held  over  the  300-kilo- 
meter course  from  Rheims  to  Amiens.  Adverse 
weather  conditions  made  these  tests  much  harder 
than  they  should  have  been  otherwise,  but  helped 
the  aviators  to  show  the  good  qualities  of  their 
machines.  Eight  passed  the  tests  successfully. 
The  machines,  pilots,  and  speed  attained  were  as 
follows : 


Pilot 

Weyraan 
Moineau 
Prevost 
Bregi 
Fischer 
Barra 
Renaux 
Frantz 


Machine 
Nieuport  i 
Br^guet  2 
Deperdussin  i 
Breguct  2 
H.    Fa  nil  an  2 
M.  Farinan  2 
M.  Farman  2 
Savary  2 


Motor 
Gnome 
Gnome 
Gnome 
Gnome 
Gnome 
Renault 
Renault 
Labor 


Time  for  300 

Kilometers 
hrs.  33'  52%" 
hrs.     9'  Hi%" 
hrs.  21'     5"' 
hrs.  2(i'  47" 
hrs.  33'     5" 
hrs.  56'  13%" 
hrs.     8'  40" 
hrs.  27'  48" 


Av.  Speed 
116.976 
95.1 
89.515 
87.047 
8i.474 
76.196 
72.38 
67.210 


1  Monoplane. 

2  Biplane. 

Thus  in  the  short  space  of  two  years  the  mili- 
tary aeroplane  had  been  developed  mechanically 
from  an  experiment  to  a  thing  which  gave  serv- 
ice of  a  kind  which  no  other  instrument  or 
mechani.sm  could  give.  Its  possibilities  had 
been  defined  and  its  purposes  had  been  extended 
^and  made  it  a  valuable  military  unit. 

Following  the  French  military  competition 
England,  Germany,  and  Austria,  organized 
competitions  of  similar  character.  England, 
who  had  not  until  then  taken  steps  to  introduce 
aviation  in  the  military  establishment,  organized 
a  competition  to  take  place  during  the  year  1912, 
whose  conditions  were  close  to  100  per  cent. 


i 


THE  EVOLUTION  OF  MILITARY  AVIATION 


229 


more  severe  than  the  conditions  of  the  French 
mihtary  contest,  as  follows: 

The  prizes  to  be  awarded  by  the  War  Office 
on  the  recommendation  of  a  Committee,  which 
will  judge  the  tests  and  will  decide  whether 
any  machine  submitted  is  to  be  subjected  to  any 
test. 

A. — Prizes  open  to  the  world  for  aeroplanes 
made  in  any  country : 
First  prize.  .£4,000     Second  prize.  .£2,000 

B. — Prizes  open  to  British  subjects  for  aero- 
planes manufactured  M'holly  in  Great  Britain, 
except  the  engines: 

First  prize .  .  £l ,.500     Two  2d  prizes .  .  £1,000 
Three  3d  prizes.  .£500  each 

No  competitor  to  take  more  than  £.5,000. 
The  War  Office  to  reserve  the  right  to  vary  the 
proportions  of  totals  under  A  and  B  between 
the  various  prizes  if  the  merits  of  the  machines 
warrant  it,  or  to  withhold  any  prize  if  there  is 
no  machine  recommended  for  it  by  the  Testing 
Committee. 

The  War  Office  to  have  the  option  of  purchas- 
ing for  £1,000  any  machine  awarded  a  prize. 

The  owners  of  10  machines  which  are  sub- 
mitted to  all  the  flying  tests  and  are  not  awarded 
a  prize  to  receive  £100  for  each  machine  so 
tested. 

Oil  and  petrol  to  be  supplied  free  for  the  tests. 

The  place  of  delivery  of  aeroplanes  entered 
for  the  con]])etition  will  be  announced  later. 

The  following  conditions  are  those  required 
to  be  fulfilled  by  a  military  aeroplane: 

1.  To  be  delivered  in  a  packing  case  suitable 
for  transport  by  rail  and  not  exceeding  32  ft.  9 
ft.  by  9  ft.  The  case  nmst  be  fitted  with  eye- 
bolts  to  facilitate  handling. 

2.  Carry  a  live  load  of  3.50  lbs.  in  addition  to 
its  eqm'pment  of  instruments,  etc.,  with  fuel  and 
oil  for  4^/4  hours. 

3.  Fly  for  three  hours  loaded  as  in  Clause  2 
and  maintain  an  altitude  of  4500  ft.  for  one 
hour,  the  first  1000  ft.  being  attained  at  the  rate 
of  200  ft.  a  minute,  although  a  rate  of  rise  of 
300  ft.  per  minute  is  desirable. 

4.  Attain  a  speed  of  not  less  than  55  m.p.h.  in 
a  calm  loaded  as  in  Clause  2. 

5.  Plane  down  to  ground,  in  a  calm  from  not 


more  than  1000  ft.  with  engine  stopped,  during 
which  time  a  horizontal  distance  of  not  less  than 
6000  ft.  must  be  traversed  before  touching, 

6.  Rise  without  damage  from  long  grass, 
clover,  or  harrowed  lands  in  100  yards  in  a  calm, 
loaded  as  in  Clause  2. 

7.  Land  without  damage  on  any  cultivated 
ground,  including  rough  plowed,  in  a  calm, 
loaded  as  in  Clause  2,  and  pull  up  within  75 
yards  of  the  point  at  which  it  first  touches  the 
ground  when  landing  on  smooth  turf  in  a  calm. 
It  must  be  capable  of  being  steered  when  run- 
ning slowly  on  the  ground. 

8.  Be  capable  of  change  from  flying  trim  to 
road  transport  trim,  and  travel  either  on  its  own 
wheels  or  on  a  trolley  on  the  road ;  width  not  to 
exceed  10  ft. 

9.  Provide  accommodation  for  a  pilot  and  ob- 
server, and  the  controls  must  be  capable  of  use 
either  by  pilot  or  observer. 

10.  The  pilot  and  observer's  view  of  the  coun- 
try below  them  to  front  and  flanks  nmst  be  as 
open  as  possible,  and  they  should  be  shielded 
from  the  wind,  and  able  to  communicate  with 
one  another.  ; 

11.  All  parts  of  aeroplane  must  be  strictly  in- 
terchangeable, like  parts  with  one  another  and 
with  spares  from  stock. 

12.  The  maker  shall  accurately  supply  the 
following  particulars,  which  will  be  verified  by 
official  test:  (a)  The  h.p.  and  the  speed  given 
on  the  bench  by  the  engine  in  a  six  hours'  run. 
(b)  The  engine  weight,  complete  (general  ar- 
rangement drawing),  and  whether  air  or  water- 
cooled,  (c)  The  intended  flying  speed,  (d) 
The  gliding  angle,  (e)  Weight  of  entire  ma- 
chine. (/)  Fuel  consumption  per  hour  at  de- 
clared h.p.  {g)  Oil  consumption  per  hour  at 
declared  h.p.     (h)   Capacity  of  tanks. 

13.  The  engine  must  be  capable  of  being 
started  up  by  the  pilot  alone. 

14.  Other  desirable  attributes  are:  (a) 
Stand  still  with  engine  running  without  being 
held.  Engine  preferably  capable  of  being 
started  from  on  board,  (h)  Effective  silencer 
fitted  to  engine,  (c)  Strain  on  pilot  as  small 
as  possible,  (d)  Flexibility  of  speed;  to  allow 
of  landings  and  observations  being  made  at  slow 
speeds  if  required,  while  reserving  a  high  acceler- 


230 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


ation  for  work  in  strong  winds,  (e)  Good 
glider,  with  a  wide  range  of  safe  angles  of  de- 
scent, to  allow  of  choice  of  landing  places  in  case 
of  engine  failures.  (/)  It  is  desirable  that  the 
time  and  nunil)er  of  men  required  for  the  change 
from  flying  trim  to  road  trim,  or  packed  for 
transport  by  rail,  and  vice  versa,  should  be  small, 
and  these  will  be  considered  in  judging  the  ma- 
chine. The  time  for  changing  from  road  trim 
and  packed  condition  to  flying  trim  to  include 
up  to  the  moment  of  leaving  the  ground  in  flight, 
allowance  being  made  for  difficulty  in  starting 
engine,  (g)  Stability  and  suitability  for  use  in 
bad  weather,  and  in  a  wind  averaging  2.5  miles 
per  hour  30  ft.  from  the  ground  without  undue 
risk  to  the  i^ilot.  Stability  in  flight  is  of  great 
importance.  (//)  The  packing  case  for  rail 
transport  to  be  easily  dismantled  and  assembled 
for  use,  and  when  dismantled  should  occupy  a 
small  space  for  storage. 

The  Kaiser's  Prize  for  a  Motor  Competition 

Until  the  French  military  competition,  Ger- 
many had  done  little  to  develop  aviation.  She 
had  concentrated  all  her  efforts  on  the  large 
dirigil)les,  and  the  only  aeroplanes  in  Germany, 
with  the  exception  of  the  Etrich  type,  were 
French  tyi)es  or  copies  of  French  and  Wright 
types. 

But  German  aviators  in  the  military  ma- 
noeuvers  of  1911  clearly  demonstrated  the  value 


of  aviation,  and  Prince  Henry  of  Prussia,  who 
had  hitherto  sponsored  aviation  without  sup- 
port, urged  an  appropriation  of  $7,500,000  for 
aviation.  As  a  result  of  the  good  work  of  the 
German  aviators,  on  January  27,  1912,  the 
Kaiser  offered  a  prize  of  .50,000  marks  to  en- 
courage the  development  of  German  aero- 
motors.  The  letter  offering  the  prize  read  as 
follows : 

To  develop  aviation  in  Germany,  I  desire  to  offer, 
out  of  my  private  purse,  a  prize  of  50,000  marks,  to 
be  given  on  the  occasion  of  my  next  patron  saint's 
day,  January  27,  1913.  The  contest,  examination, 
and  tests  will  be  arranged  and  conducted  by  a  com- 
mittee composed  of  members  of  the  Imperial  Automo- 
bile Club,  Imperial  Aero  Club,  members  of  the  German 
Automobile  Constructors'  Association,  and  delegates 
of  the  Imperial  Office  of  the  Interior,  the  Navy,  War 
Department,  Department  of  Public  Instruction,  and 
Polytechnic  School  of  Berlin. 

I  write  you  to  draw  up  and  present  to  me  the  report 
of  the  finding  of  the  committee  by  the  beginning  of 
January,  1913. 


(Signed) 
Berlin,  January  27,  1912. 


WiLUAM,  I.  R. 


The  offering  of  this  prize  was  like  a  signal  to 
the  German  nation  to  take  up  the  work  of  avia- 
tion. 

The  Aerial  League  of  Germany  started  a 
public  subscription  which  brought  in  7,234,500 
marks.  The  purpose  of  the  league  was  to  train 
within  the  shortest  time  as  large  a  number  as 
possible  of  aviation  pilots,  to  form  a  reserve,  and 
to  encourage  the  general  development  of  avia- 


PartUl  riew  of  tbe  90  Frenrh  a<-ru|ilaneg  which  participated  in  tlic  first  military  aeronautic  review— held  nt  Buc,  I-'rance,  in  I9I3. 


THE  EVOLUTION  OF  MILITARY  AVIATION 


281 


tion  in  Germany.  Following  are  some  of  the 
results  obtained: 

The  number  of  pilots  was  230  at  the  end  of 
1912;  it  increased  to  000  by  the  end  of  1913. 
The  constructors  of  aeroplanes  numbered  less 
than  20  in  1912 :  they  increased  to  50  by  the  end 
of  1913.  The  developments  due  to  the  eflForts 
of  the  Aerial  League  led  the  Reichstag  to  pass 
a  bill  providing  for  an  expenditure  of  $35,000,- 
000  for  military  aeronautics  during  the  next  five 
years. 

During  the  first  month  of  1914  inducements 
offered  by  the  Aerial  liCague  of  Germany  led  to 
the  breaking  by  German  aviators  of  all  world 
records.  By  the  middle  of  July  the  non-stop 
endurance  record  was  brought  up  to  24  hours, 
12  minutes,  by  Reinhold  Boehm,  and  the  alti- 
tude record  to  26,246  feet,  by  Heinrich  Oelrich. 
Over  one  hundred  other  records  similar  to  the 
above  were  made.  For  instance,  Basser  and 
Landsmann  made  continuous  flights  of  18  hours, 
11  minutes  and  21  hours,  49  minutes,  repect- 
ively.  In  one  of  these  flights  Landsmann  cov- 
ered 1335  miles,  the  longest  distance  ever 
traveled  by  man  in  one  day.  Among  the 
records  for  altitude  was  that  of  21,654  feet,  made 
by  Otto  Linnekogel. 

The  secret  of  these  successes  was  the  motor. — 
a  Mercedes, — developed  as  a  result  of  the  in- 
terest created  by  the  Kaiser's  prize. 

-    Aeroplanes  First  Used  for  Military  Purposes 
W  in  the  Italian-Turkish  War 

The  first  aeroplane  to  be  used  imder  condi- 
tions approximately  warfare  was  the  Wright 
machine  belonging  to  Mr.  Robert  J.  Collier. 
He  was  then  president  of  the  Aero  Club  of 
America,  and  loaned  his  machine  to  the  United 
States  Government  for  use  on  the  Mexican  bor- 
der in  1911. 

The  first  employment  of  aero])lanes  in  actual 
war  was  in  Tripolitania,  during  the  Italian- 
Turkish  war  in  1911. 

French  Aviation  Developed  by  Public 
Interest 

It  was  in  1910,  that  the  late  General  Stephane 
Brun,  French  Minister  of  War,  took  steps  to 
develop  aviation  in  France.     In  so  doing  he 


overruled  the  objections  of  his  staff,  who  con- 
demned the  aeroplane  as  practically  useless,  and 
recommended  concentration  of  effort  on  build- 
ing dirigibles.  Up  to  that  time  nothing  had 
been  done  to  develop  military  aviation  in  France. 

During  that  year  General  Brun  arranged  for 
the  participation  of  aeroplanes  and  dirigibles  in 
the  French  military  manoeuvers,  and  also  em- 
ployed leading  civilian  aviators  in  these  ma- 
noeuvers. The  innovation  proved  a  great  suc- 
cess and  created  tremendous  public  interest. 

The  manoeuvers  were  followed  by  the  "Circuit 
of  Eastern  France,"  which  also  was  a  great  suc- 
cess. In  that  cii'cuit  the  aviators  covcM-cd  a  dis- 
tance of  500  miles,  accomplishing  what  was  then 
considered  impossible.  The  success  of  this  cir- 
cuit led  to  holding,  in  1911,  the  Paris-Madrid 
Race,  the  Paris-Rome  Race,  the  European  Cir- 
cuit, and  the  British  Circuit,  in  all  of  which 
French  aviators  participated,  carrying  away  the 
most  important  prizes.  These  circuits  were  fol- 
lowed by  military  manoeuvers  in  which  French 
aviators  again  gave  a  good  account  of  them- 
selves. 

The  Paris  Aero-Show  that  winter  was 
thronged  by  an  enthusiastic,  patriotic  public 
which  expressed  its  enthusiasm  in  many  ways. 
At  the  time  of  the  show  an  estimate  was  before 
the  French  Chamber  of  Deputies  appropriating 
11,000,000  francs  for  military  aviation.  That 
sum  seemed  insufficient  to  the  enthusiastic  patri- 
ots and  they  said  so.  The  French  Minister  of 
War  who  had  succeeded  General  Brun  thought 
the  sum  sufficient,  and  explained  that  it  was 
much  more  than  had  been  spent  the  year  before 
for  this  purpose.  The  patriots  were  not  con- 
cerned with  what  had  been  done  the  year  before ; 
they  wanted  aeroplanes  now,  and  wrote  long  let- 
ters to  the  newspapers.  The  press  became  in- 
terested and  came  out  strongly  in  support  of  the 
demand  for  more  aeroplanes,  pointing  to  the 
splendid  Salon  show  as  an  example  of  what 
French  genius  could  do.  People  all  over  the 
country  became  interested  and  went  to  the 
Salon.  The  sight  of  fourscore  aeroplanes  ex- 
hibited there  and  contact  with  the  airmen  who 
had  brought  France  new  glory  did  the  rest. 
Presently  the  provinces  joined  in  the  fight,  and 
the  Minister  of  War  was  just  getting  ready  to 


232 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


The  first  use  of  aero- 
planes in  war  during  the 
Italian-Turkish  War.  An 
Italian  airscout  is  here 
shown  starting  on  a 
scouting  trip  outside 
Tripoli,  Feb.,  1912. 


reply  to  .scores  of  memorandums  from  repre- 
sentatives of  different  departments  when  the 
ministry  fell. 

The  advent  of  the  new  Minister  of  War,  M. 
Alexandre  Millerand,  at  this  critical  juncture 
was  most  propitious.  M.  Millerand  believes  in 
aviation.  Though  a  Socialist,  he  is  intently  pa- 
triotic and  believes  that  a  nation  should  be  well 
armed  against  contingencies.  His  first  move 
was  to  announce  his  full  sympathy  with  the 
movement  and  to  increase  the  appropriation  for 
military  aviation  to  3,000,000  francs.  This  set- 
tled matters  and  pleased  all  concerned.  Things 
were  about  to  quiet  down  when  it  became  known 
that  Prince  Henry  of  Prussia  had  advocated  an 
expenditure  of  $7,.'500,000  for  aviation,  and  that 
the  Kaiser  had  offered  a  prize  of  .50,000  marks 
to  encourage  the  development  of  German  aero- 
motors. 

Next  it  was  made  public  that  the  makers  of 
the  Deperdussin  monoplane,  the  military  aero- 
plane with  which  Vedrines  and  Prevost  had  just 
made  two  splendid  records,  and  which  Vedrines 
had  used  to  fly  over  the  Chamber  of  Deputies 
and  drop  handbills  reading,  "Give  France  More 
Aeroplanes,"  had  received  a  communication 
from  a  leading  German  concern.  It  was  an  of- 
fer to  buy  the  rights  to  construct  that  machine 
in  Germany,  but  advised  that  in  case  the  offer 


was  declined  the  German  firm  would  go  ahead 
and  construct  the  machine  without  permission. 

These  three  events  had  a  tremendous  effect. 
It  was  accepted  as  a  challenge  from  Germany. 
Old  scores  were  brought  up,  and  the  old  wounds 
of  1870  were  reopened.  But  the  result  was  not 
an  outburst  of  antagonism,  as  might  have  been 
expected.  Little  time  was  spent  in  talking 
about  the  challenge.  Interest  turned  at  once  to 
the  matter  of  getting  means  to  make  France  su- 
preme in  the  line  in  which  she  leads — aviation. 

On  February  11,  1912  a  meeting  was  held  at 
the  Sorbonne,  which  bids  fair  to  become  a  his- 
torical event.  It  was  held  under  the  auspices 
of  the  Association  Generale  Aeronautiqiie  in  or- 
der to  devise  plans  to  start  a  national  movement 
to  make  France  supreme  in  aerial  matters,  and 
was  attended  by  the  highest  civil  and  military 
authorities.  The  meeting  was  open  to  the  pub- 
lic, who  poured  in  until  the  vast  Sorbonne  hall 
was  packed  to  its  capacity.  The  following  re- 
port by  the  Frantz-Reichel,  the  French  veteran 
reporter,  gives  an  idea  of  what  happened : 

Representative  Gabriel  Bonvalot  began  speaking. 
With  extended  arms  and  a  voice  vibrating  with  patri- 
otic emotion  he  made  his  appeal. 

"France  need.s  the  fourth  arm,"  said  he,  "and  at 
once.  The  other  side  of  the  Rhine  is  preparing;  it 
is  the  Emperor  who  has  given  the  war-cry.     Let  us 


THE  EVOLUTION  OF  MILITARY  AVIATION 


233 


prepare  against  this;  let  us  unite  our  activities  and 
efforts  in  a  manifestation  which  will  make  our  country 
supreme  in  aerial  armament. 

"I  don't  cry  unto  you :  'Help  us !'  I  cry  unto  you : 
'help  yourself.'  We  must  have  aerodromes;  we  must 
have  hangars,  aeroplanes,  and  money.  Let  us  take 
stock  and  let  each  give  according  to  his  resources. 
Little  or  much,  gold  or  pennies, — it  does  n't  matter. 
What  we  want  is  the  manifestation  of  your  love  of 
country.     Say,  will  you?" 

The  audience  roared  "Yes!"  enthusiastically. 

"Thanks,"  said  he. 

But  he  was  unable  to  continue.  The  gathering  was 
in  uproar,  and  each  person  was  busy  taking  stock  of 
his  resources. 

The  generals  present  gave  their  caps  to  the  avia- 
tors, and  the  latter  went  up  and  down  the  aisles.  But 
there  were  not  enough  caps,  and  the  audience  cried, 
"More,  more!"  Ladies  then  took  the  military  avia- 
tors' caps  and  went  around  to  collect.  But  again 
these  proved  not  enough.  As  the  crowd  in  the  gal- 
leries was  growing  impatient,  the  military  students 
took  their  own  caps  and  went  around. 

Following  this  touching  and  curious  scene,  the  col- 
lection was  emptied  on  a  table  before  the  generals, 
senators  and  deputies,  who  made  piles  of  the  gold, 
silver,  and  copper,  and  added  up  the  total.  Gabriel 
Bonvalot  rose  again  and  said: 

"You  have  given  2274  francs.  This  is  well.  But 
I  have  other  good  news  to  announce.  While  you  were 
giving,  others  gave,  and  here  is  what  the  General  Aero- 
nautical Association  has  collected  for  the  Committee 
jof  National  Aviation.  Listen !  The  Aerial  Associa- 
tion of  Picardie,  5000  francs ;  M.  Jacques  Balsan,  at 
Chateauroux,  one  hangar ;  at  Pau,  another  hangar  for 
four  aeroplanes  and  a  house  for  twenty  military  avi- 
ators ;  the  committee  of  Orleans,  one  aeroplane  for  the 
Fifth  Army  Corps ;  the  committee  of  Cher  and  Prince 
d'Arenberg,  three  aeroplanes ;  the  committee  of  Pi- 
cardie, one  aeroplane;  the  committee  of  Charentes, 
100  acres  of  land;  the  committee  of  Pointiers,  two 
hangars  and  an  aeroplane;  M.  Henry  Deutsch,  one 
aeroplane;  and,  finally,  M.  Michelin,  100,000  francs  to 
pay  for  the  apprenticeship  of  young  men  whose  per- 
sonal means  do  not  allow  them  to  put  their  courage  at 
the  disposal  of  the  nation." 

This  announcement  was  received  with  a  thunder  of 
acclamations. 

Captain  Bellenger,  the  pioneer  military  aviator, 
representing  the  Minister  of  War,  IVI.  Millerand,  spoke 
next.  He  demonstrated  with  the  authority  of  an  of- 
ficer and  an  aviator  the  important  role  played  by  the 
aeroplane  in  war,  and  he  recalled  the  painful  experi- 
ence of  1870,  in  order  to  make  the  people  understand 
the  lesson — understand  that  they  had  been  defeated 
by  the  ignorance  of  the  chiefs  of  the  French  army  con- 
cerning the  movements  and  plans  of  the  enemy.     He 


recalled  Weissemboyrg,  Froeschwiller,  and  other  pain- 
ful instances,  and  showed  that  if  similar  circumstances 
recurred,  they  could  not  bring  the  same  terrible  con- 
sequences, provided  France  had  aeroplanes  in  her 
army.  He  ended  by  quoting  conclusive  examples  of 
the  role  played  by  the  aeroplane  in  actual  warfare  in 
Tripoli. 

Following  him.  Senator  Reymond  spoke  on  the  ne- 
cessity of  giving  France  a  strong  aerial  organization. 
Then  M.  Millevoy  spoke  of  the  great  value  of  the  aero- 
plane, of  its  convincing  qualities  in  furthering  peace 
and  making  France  aerially  supreme. 

M.  George  Clemenceau,  though  an  invalid  forbidden 
by  his  doctor  to  take  part  in  the  event,  was  conquered 
by  enthusiasm  and,  an  invalid  no  longer,  rose  and  pas- 
sionately urged  the  people  to  assist  in  the  national 
movement. 

When,  finally,  the  addresses  were  ended.  Mile.  Vix 
of  the  Opera  sang  an  air  from  the  "Vivandiere,"  in 
which  all  joined.  And  thus  ended  this  historic  meet- 
ing. 


On  the  day  after  the  Sorbonne  meeting  the 
daily  newspaper  "Matin"  started  a  national  sub- 
scription with  a  contribution  of  .50,000  francs, 
an  example  at  once  followed  by  the  "Petit 
Journal"  and  the  "Petit  Parisien,"  and  subse- 
quently by  other  publications  throughout  the 
country.  Soon  donations  came  from  all  sides. 
States,  departments,  cities,  towns,  villages,  clubs 
and  universities;  political,  educational,  indus- 
trial, sportive,  and  social  associations — all  con- 
tributed. In  most  cases  the  plan  of  contribution 
was  to  give  an  army  aeroplane  which  would  bear 
the  name  of  the  state,  department,  or  body  mak- 
ing the  gift.  Large  communities  contributed 
as  many  as  six  aeroplanes.  In  some  poor  com- 
munities the  inhabitants  contributed  five  cents 
each;  in  others  school-children  contributed  one 
cent  each;  in  a  home  of  destitutes  the  inmates 
offered  to  go  without  certain  necessities  to  con- 
tribute a  few  cents  each.  Individual  contribu- 
tions varied  in  type  from  checks  for  100,000 
francs,  given  by  some  rich  persons,  to  a  month 
of  services  offered  by  a  nurse  who  did  not  have 
any  cash.  They  included  songs  written  by 
chansonniers  of  Montmartre  fame,  and  the 
statue  "La  Defense,"  donated  by  the  famous 
sculptor,  Rodin.  Inside  of  a  month's  time  the 
collected  fund  amounted  to  over  1,500,000 
francs.     The  total  of  the  French  public  sub- 


234 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


scription  at  the  beginning  of  the  present  war 
was  6,114,846  francs. 

Board  of  Governors,  Aero  Club  of  America: 

Gentlemen — As  per  authorization  of  your  Executive 
Committee,  dated  May  19,  1915,  and  February  23, 
1916,  I  have,  with  Messrs.  Henry  A.  Wise  Wood  and 
Henry  Woodhouse,  attended  to  the  affairs  of  the  Na- 
tional Aeroplane  Fund,  and  I  take  pleasure  in  pre- 
senting herewith  a  brief  report  of  the  work  of  the 
National  Aeroplane  Fund,  and  an  audit  of  so  much 
of  the  fund  as  passed  through  the  hands  of  the  Execu- 
tive Committee  of  the  Aero  Club  of  America. 

This  audit  shows  that  the  sum  of  .$171,031.17  was 
received  direct,  $147,314.92  of  which  was  disbursed  to 
carry  out  the  purposes  for  which  the  money  was  sub- 
scribed. Of  the  balance,  which  amounts  to  .$23,- 
716.25,  the  sum  of  $20,876.76  is  obligated  for  the 
$20,000  set  aside  for  the  prizes  for  the  National  Aerial 
Derby,  prizes  for  model  aerojjlane  competitions,  ex- 
penses for  the  National  Aerial  Coast  Patrol  Commis- 
sion, etc. 

In  addition  to  the  sum  so  subscribed,  there  were 
given  to  the  National  Aeroplane  Fund  aeroplanes  and 
a  course  of  training  for  militiamen  and  civilians,  for 
the  purpose  of  lieli)ing  to  build  our  aerial  defenses, 
valued  at  $94,000,  which  are  not  included  with  the 
cash  subscriptions  to  the  fund. 

In  addition,  the  funds,  aeroplanes,  and  training  se- 
cured for  different  states,  in  different  ways,  not  shown 
on  the  books  of  the  fund,  but  all  being  the  direct  result 
of  the  work  of  the  administrators  of  the  National 
Aeroplane  Fund,  and  being  valuable  for  what  they 
contributed  to  the  building  of  our  aerial  defenses, 
amounted  to  about  $109,300. 

This  makes  the  total  cash  value  of  the  contributions 
secured  through  the  efforts  of  the  administrators  of 
the  .National  Aeroplane  Fund,  for  the  upbuilding  of 


our  aerial  defenses  and  developing  our  aeronautic  re- 
sources, $378,381.17.  The  value  of  resources  devel- 
oped is  hard  to  estimate. 

Furthermore,  by  means  of  the  National  Aeroplane 
Fund  educational  campaign,  public  interest  was 
aroused  to  demand  of  Congress  suitable  a])propria- 
tions  for  aeronautics  in  the  Army,  Navy,  Militia, 
Aerial  Reserve  Corps  and  Coast  Guard,  which  resulted 
in  the  appropriation  for  the  diff'.>rent  services  of  the 
sum  of  $18,000,000. 

As  can  be  seen  from  the  reports  covering  the  differ- 
ent lines  of  activity  developed  by  the  National  Aero- 
plane Fund,  which  was  started  in  the  spring  of  1915, 
when  American  aeronautics  was  at  its  lowest  ebb,  the 
National  Aeroplane  Fund  succeeded  in  developing 
aeronautics  in  the  Army,  Navy,  National  Guard,  Na- 
val Militia ;  among  college  men,  in  the  Coast  Guard, 
and  a  dozen  other  fields. 

This  movement  was  started  in  the  early  spring  of 
1915,  after  Congress  had  adjourned  and  the  inter- 
national situation  grew  serious  enough  to  make  this 
country  take  stock  of  its  defenses.  There  were  at  the 
time  only  about  a  dozen  aeroj)lanes  in  commission  in 
the  Army  and  Navy  combined,  when  we  should  have 
had  one  hundred  times  that  number,  and  there  were 
no  prospects  of  relief,  since  the  last  Congress  had  al- 
lowed but  a  fraction  of  the  amount  needed  for  aero- 
nautics. The  maneuvers  of  the  National  Guard  and 
Naval  Militia  of  the  states  were  being  planned,  but  in 
no  case  was  an  aeroplane  to  be  employed — the  reason 
being  that  there  were  no  funds  available  to  pay  for 
aeroplanes  or  for  training  Militia  officers  in  aviation. 

The  Aero  Club  of  America,  the  National  aeronautic 
body,  which  has  fostered  the  development  of  aeronau- 
tics in  America  since  1905,  realizing  the  necessity  of 
bringing  immediate  relief,  decided  to  wait  no  longer 
for  the  Government  to  do  its  duty.  It  took  steps  to 
contribute  materially  toward  })roviding  aeronautical 


The  flr»t  tractor  liiplanc  in  America.    Constructed  l)y  Captain  Jiiims  V.  .Martin  in  August,  1911.    'Vhv  first  fliglit  toolt  place  in 
November,  1911,  at  Nassau  Boulevard,  I,.  I.     It  was  equipped  with  a  100  h.p.  Gnome  motor. 


THE  EVOLUTION  OF  MILITARY  AVIATION 


285 


equipment  and  instituted  the  National  Aeroplane 
Fund  for  the  purpose  of  developing  our  aeronautical 
resources,  oi-ganizing  aviation  units  in  the  Militia  of 
the  States,  building  an  aeronautical  reserve,  and  creat- 
ing in  a  general  way  sources  of  supply  of  personnel 
and  equipment. 

In  the  educational  campaign,  which  was  the  back- 
bone of  the  National  Aeroplane  Fund,  which  resulted 
in  2,000,000  })ieces  of  literature  being  distributed  dur- 
ing eighteen  months,  the  committee  has  had  the  hearty 
cooperation  of  the  press  of  the  United  States.  We 
have  received  an  average  of  sixty  clippings  a  day  re- 
garding the  work  of  the  Aero  Club  of  America  during 
these  eighteen  months,  including  hundreds  of  editori- 
als, not  a  single  one  of  which  spoke  unfavorably  of  the 
National  Aeroplane  Fund  or  the  work  of  the  Aero 
Club  of  America. 

The  work  of  the  National  Aerojilane  Fund  has  been 
highly  commended  by  leading  Congressmen  and  Sena- 
tors, and  was  favorably  mentioned  on  the  floor  of  the 
House  of  Representatives.  We  have  also  been  warmly 
praised  by  Washington  officials,  also  by  the  governors 
and  adjutants-general  of  the  States  and  by  hundreds 
of  contributors  to  the  fund,  and  others. 

Some  of  the  most  important  movements  started  or 
endorsed  by  the  Executive  Committee  in  connection 
with  the  campaign  to  develop  our  aerial  defenses  have 
been  adopted  and  endorsed  by  the  Administration  and 
are  as  follows: 

The  Council  of  National  Defense,  which  was  advo- 
cated by  the  Aero  Club  of  America  and  other  organ- 
izations cooperating  through  the  Conference  Commit- 
tee on  National  Preparedness  in  May,  1915,  was 
adopted  by  Congress,  and  President  Wilson  has  just 
appointed  the  seven  civilian  members  of  the  council, 
which  include  two  prominent  members  of  the  Aero 
Club  of  America. 

The  organizing  of  the  Council  of  National  Defense 
is  undoubtedly  the  most  important  step  taken  so  far 
to  develop  real  national  preparedness.  This  country 
as  a  nation  has  been  like  a  house  divided.  There  has 
been  practically  no  cooperation  between  the  Govern- 
ment, the  industries,  the  patriotic  organizations,  and 
the  people.  So  our  enormous  resources  and  extensive 
industries  have  never  been  coordinated  as  the  best  in- 
terests of  the  nation  demand.  The  Council  is  to  do 
the  coordinating,  and  we  expect  that  aeronautics  will 
greatly  benefit  from  the  coordination  of  our  aero- 
nautical resources  which  the  council  may  bring  about. 

The  large  appropriation  asked  by  the  Aero  Club 
of  America  for  aerial  defense,  which  seemed  excessive 
when  it  was  proposed,  as  it  was  six  times  greater  than 
the  estimates  submitted  to  Congress  by  the  secretaries 
of  war  and  the  navy,  was  adopted  by  Congress,  and 
close  to  $18,000,000  was  allowed  for  aerial  defense, 
instead  of  ,$3,200,000  asked  by  the  secretaries  of  war 
and  the  navy. 


The  plan  to  organize  an  Aerial  Reserve  Corps  pro- 
posed by  the  "New  York  World"  and  the  Aero  Club 
of  America,  was  authorized  on  July  13  by  President 
Wilson,  after  a  committee  of  the  club's  Executive 
Committee  called  at  the  White  House  and  recom- 
mended the  authorization  of  the  plan. 

The  j)lan  of  the  Aerial  Coast  Patrol  was  promptly 
endorsed  by  President  Wilson  and  the  secretaries  of 
war  and  navy,  and  an  appropriation  of  $1,500,000 
has  been  ]iromised  for  putting  the  plan  into  effect. 

Steps  were  taken  to  establish  aerial  coast  patrol 
units,  and  a  complete  unit  was  established  at  Port 
Washington,  Long  Island — the  Volunteer  AerisJ 
Coast  Patrol  Unit  No.  1,  organized  by  F.  Trubee 
Davison  and  eleven  other  patriotic  young  men.  This 
unit  rendered  valuable  service  in  connection  with  the 
"Mosquito  Fleet"  manoeuvers. 

A  Bill  was  introduced  in  the  Senate  to  appropriate 
the  sum  of  $1,500,000  for  establishing  units  of  the 
Aerial  Coast  Patrol  under  the  auspices  of  the  Navy, 
and  in  connection  with  the  Naval  Militia  and  Naval 
Reserves,  but  owing  to  the  shortness  of  time,  and  the 
pressure  of  legislative  business,  Congress  could  not 
act  upon  it  during  the  past  session. 

The  plan  to  use  aeroplanes  in  connection  with  the 
Coast  Guard,  for  the  Life-Saving  Service  and  Revenue 
Cutter  Service,  first  recommended  by  me  five  years 
ago,  and  since  advocated  by  the  Aero  Club  of  Amer- 
ica, and  substantially  supported  by  Byron  R.  New- 
ton, the  assistant  secretary  of  the  treasury,  has  been 
adopted  by  Congress. 

The  plan  to  use  aeroplanes  for  mail-carrying,  ad- 
vocated by  the  Aero  Club  of  America  for  several 
years,  has  been  adopted  and  the  postmaster-general 
has  invited  bids  for  mail-carrying  over  different 
routes  where  there  is  now  spent  $330,000  for  carrying 
mail  by  other  methods.  This  sum  would  be  spent  for 
aeroplane  mail-carrying  if  suitable  bids  could  be  ob- 
tained. The  post-office  authorities  are  anxious  to 
put  this  plan  in  operation  and  are  giving  every  en- 
couragement. 

The  plan  to  interest  the  universities  in  aerial  de- 
fense, which  the  Aero  Club  of  America  has  been  car- 
rying out  in  so  far  as  it  concerns  aerial  defense,  and 
which  was  frowned  upon  some  time  ago,  has  been  fol- 
lowed by  a  request  from  President  Wilson  to  the  heads 
of  the  leading  universities  to  consider  ways  and  means 
to  arrange  for  the  training  in  military  science  of  stu- 
dents in  sixteen  of  the  country's  leading  universities 
and  colleges  under  the  auspices  of  the  War  Depart- 
ment. 

Our  committee,  with  the  cooperation  of  Robert 
Bacon,  offered  a  bonus  of  $50  for  each  Harvard  un- 
dergraduate who  learned  to  fly  and  passed  the  F.  A.  I. 
pilot  tests.  Twenty-one  undergraduates  took  a 
course;  twelve  have  already  passed  the  tests.  We 
have  also  offered  three  medals  of  merit  to  each  of  the 


236 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


First  use  of  aeroplane  in 
w,ir  oonditions.  Lieut,  (now 
Brifr.-Gen.)  B.  D.  Foulois 
and  P.  Pariuelee  at  Eagle 
Pass,  March,  1911,  with  the 
aeroplane  loaned  to  the 
Army  by  Robert  J.  Collier, 
President  of  the  Aero  Club 
of  America. 


hundred  largest  universities,  having  a  total  of  about 
850,000  students,  the  medals  to  be  awarded  to  the 
three  students  who,  by  March  15,  1917,  write  the  best 
essays  on  (a)  Military  Aeronautics;  (b)  Mechanics 
of  the  Aeroplane  and  Possible  Technical  Development 
in  Aeronautics;  (c)  Possible  Application  of  Aircraft 
for  Utilitarian  Purposes. 

To  foster  progress  in  the  technical  branch  of  aero- 
nautics and  begin  the  Work  of  standardizing,  the  com- 
mittee, at  the  request  of  Thomas  A.  Edison,  organ- 
ized the  American  Society  of  Aeronautic  Engineers, 
which  now  includes  in  its  membership  all  the  promi- 
nent aeronautic  engineers.  The  society  is  now  being 
combined  with  the  Society  of  .Automobile  Engineers, 
and  Motor-Tractor  Engineers,  and  a  new  organiza- 
tion being  created  which  is  to  be  called  the  American 
Society  of  Automotive  Engineers. 

Appreciating  the  basic  value  of  Pan-Americanism 
from  the  standpoint  of  national  defense,  the  commit- 
tee started  a  movement  to  develop  Pan-American 
aeronautics.  Alberto  Santos-Dumont  was  invited  to 
conic  to  the  United  States  to  cooperate  in  this  move- 
ment. He  came,  and  has  been  traveling  through  South 
and  Central  America,  as  the  club's  representative,  and 
has  already  done  some  very  constructive  work.  The 
organization  of  the  Pan-American  Aeronautic  Fed- 
eration was  a  direct  result  of  the  work  of  the  Execu- 
tive Committee.  This  federation  is  already  a  most 
powerful  organization,  and  will  be  more  so  as  time 
goes  on.  A  large  Pan  American  Aeronautic  Exposi- 
tion is  now  being  organized  to  be  held  next  February, 
Mr.  Henry  Woodhouse,  who,  with  Mr.  Henry  A.  Wise 
Wood,  has  been  the  father  of  the  Pan-American  move- 
ment,  is   raising   the  $10,000   needed   for   the   Pan- 


American  Aviation  Trophy,  and  prizes  to  be  com- 
peted for  at  Rio  de  Janeiro  next  summer. 

Giving  a  national  defense  aspect  to  the  sport  of  fly- 
ing resulted  in  two  score  of  sportsmen  taking  up 
aviation  and  acquiring  their  own  aeroplanes  for  use  of 
national  defense  in  case  of  emergency. 

The  success  of  the  aviation  meet,  held  at  Sheeps- 
hcad  Bay  last  spring,  was  a  direct  result  of  the  work 
of  the  National  Aeroplane  Fund.  Remarkable  rec- 
ords were  made  at  this  meet,  including  non-stop  flights 
from  Newport  News  to  New  York  with  passengers. 

Subsequently,  and  with  the  hearty  cooperation  of 
the  "  New  York  World,"  a  flight  was  made  from  New 
York  to  Washington,  in  which  I  was  a  passenger,  for 
the  purpose  of  carrying  to  Washington  a  special 
edition  of  the  "New  York  World,"  which  advocated 
the  training  of  2000  aviators,  wiiich  plan  was  en- 
dorsed by  the  governors  of  practically  all  the  States. 
This  plan  to  train  2000  aviators  was  favorably  con- 
sidered by  Congress,  and  when  a  letter  sent  to  one  of 
the  Congressmen  with  a  copy  of  the  "World"  was  read 
on  the  floor  of  the  House  of  Representatives,  the 
House  applauded  and  the  letter  was  ordered  printed 
in  the  "Congressional  Record." 

Subsequently,  and  with  the  hearty  cooperation  of 
Rear-Admiral  Robert  E.  Peary,  Congressmen  Kahn, 
Lieb,  Hulbert,  and  Senators  Johnson  and  Sheppard, 
and  Government  officials,  an  exhibition  of  four  aero- 
planes was  held  in  Washington.  It  lasted  about  two 
weeks  and  assisted  greatly  in  educating  the  members 
of  both  Houses  and  making  them  realize  the  necessity 
of  increasing  the  appropriations  for  aerial  defense. 

It  was  also  through  the  interest  created  by  the  Na- 
tional Aeroplane  Fund  that  Mr.  Ralph  Pulitzer  of- 


THE  EVOLUTION  OF  MILITARY  AVIATION 


287 


fered  the  Pulitzer  trophy,  instituting  the  National 
Aerial  Derby,  which  is  to  take  place  annually,  and  for 
which  there  has  been  set  aside  $20,0C0  to  be  given  as 
prizes,  this  sum  being  part  of  the  contributions  made 
to  the  National  Aeroplane  Fund  by  Mr.  Emerson  Mc- 
Millin,  who  requested  that  his  contributions  be  spent 
at  the  discretion  of  the  Board  for  whatever  purposes 
the  Board  deemed  best. 

To  interest  the  younger  generation  in  aeronautics, 
prizes  were  offered  from  the  National  Aeroplane  Fund 
for  model  aeroplane  contests,  in  which  more  than 
twenty  model  aero  clubs  in  different  parts  of  the  coun- 
try participated.  Knowing  that  the  Wright  Broth- 
ers themselves  became  interested  in  aeronautics 
through  a  toy  helicopter,  we  realized  that  offering 
prizes  to  encourage  the  younger  generation  may  re- 
sult in  finding  geniuses  who  may  eventually  create,  or 
develop  or  invent  something  which  will  be  of  great 
value  to  mankind.  To  interest  the  still  younger  gen- 
eration, at  the  time  when  the  National  Educational 
Association  of  the  United  States  held  its  convention 
in  New  York,  steps  were  taken  to  interest  in  aeronau- 
tics the  60,000  school  teachers  who  attended  the  con- 
vention.    An  aeroplane  exhibition  was  arranged  espe- 


cially for  the  teachers,  and  they  were  given  copies  of 
"Flying,"  donated  by  the  publishers,  containing  the 
history  of  the  development  of  aeronautics  from  the 
earliest  ages ;  and  a  diploma  to  be  awarded  to  a  pupil 
in  each  school  who  writes  the  best  composition  on 
aeronautics. 

The  foregoing  is  only  a  brief  outline  of  what  has 
been  accomplished  by  the  National  Aeroplane  Fund. 
It  would  take  many  pages  to  give  the  less  prominent 
achievements. 

The  committee  received  substantial  and  hearty  sup- 
port from  the  following  governors  of  the  club:  Rear- 
Admiral  Robert  E.  Peary,  Cortlandt  F.  Bishop,  John 
Hays  Hammond,  Jr.,  Evert  Jansen  Wendell,  diaries 
Jerome  Edwards,  Albert  Bond  Lambert,  George  M. 
Myers,  Henry  B.  Joy,  Rodman  Wanamaker,  and  the 
late  Samuel  H.  Valentine. 

It  is  hard  for  me  to  find  words  that  will  adequately 
express  the  value  of  the  work  done  by  Mr.  Henry 
Woodhouse  in  connection  with  the  National  Aero- 
plane Fund.  He  subscribed  the  first  $1000  to  make 
it  possible  to  begin  the  National  Aeroplane  Fund,  and 
then  made  additional  contributions  during  the  cam- 
paign.    He  has  given  his  entire  time,  practically  six- 


H 

jmm 

'^y"-mmy^_      r-^  M 

1" 

__ — : ^z!!32£*JBSLaH^HHHBI^^^^^I 

Looking  down  on  a  German  Gotha  resting  on  the  ground.     (British  official  photo.) 


238 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


teen  hours  a  day,  every  day,  including  Sundays  and 
holidays,  to  this  work,  practically  only  leaving  the 
club  house  on  occasions  when  he  had  to  deliver  ad- 
dresses and  to  attend  meetings  or  make  trips  of  in- 
spection in  connection  with  the  furthering  of  this 
campaign.  He  has  done  this  without  compensation 
or  expectation  of  compensation. 

Very  sincerely  yours, 

Alan  R.  Hawley, 
Chairman. 


Firing  Guns,   Dropping   Large  Bombs,   and 
Two-Engined  Aeroplanes  Once  Consid- 
ered Impossibilities 

The  writer  clearly  remembers  that  in  1910-13 
the  firing  of  machine-guns  and  the  dropping  of 
large  bombs  from  aeroplanes  were  considered 
impossibilities.  It  was  lield  that  tlie  recoil  of  a 
gun  would  upset  the  aeroplanes ;  while  the  drop- 
ping of  weight  of  more  than  fifty  pounds  would 
upset  the  aeroplane.  For  that  reason  it  was 
held  that  aeroplanes  could  only  be  used  for 
scouting,  directing  artillery  fire,  and  taking 
photographs.  The  development  of  speedy  aero- 
planes was  discouraged.  Those  who  expressed 
the  possibility  of  equipping  aei'oplanes  with  two 
or  more  motors  were  considered  visionary,  the 
general  opinion  being  that  an  aeroplane 
equipped  with  two  motors  would   fail.     Two 


reasons  were  given:  First,  the  machine  would 
be  unable  to  lift  its  own  weight ;  secondly,  if  one 
motor  stopped,  the  other  motor  would  make  the 
machine  spin. 

Speed  in  aeroplanes  was  developed,  there- 
fore, entirely  by  private  efforts,  mainly  by 
sportsmen  and  aero-clubs  in  connection  with  the 
annual  competition  for  the  Gordon-Bennett 
Cup.  As  early  as  1912  this  trophj'  was  won  by 
a  flight  of  over  one  hour  at  a  speed  of  10.5  miles 
per  hour.  In  1913  tlie  winner  of  the  Gordon- 
Bennett  Cup  made  a  speed  of  124  miles  an  hour 
for  about  one  hour. 

In  1913  a  prize  of  $15,000  was  offered  by  Mr. 
Edwin  Gould,  a  member  of  the  Aero  Club  of 
America,  in  a  competition  for  twin-motored 
aeroplanes,  but  it  was  not  won,  although  the 
conditions  required  only  a  flight  of  about  one 
hour. 

Following  is  given,  for  historic  purposes,  a 
table  of  the  performances  required  by  the  British 
War  Office  for  aeroplanes  of  different  types  on 
February  9,  1914. 

British  Army  Tests  for  Aeroplanes  in  1914 

1.  The  Chief  Inspector  of  Military  Aero- 
nautics is  prepared,  on  the  request  of  an  aero- 
plane constructor,  to  put  an  aeroplane  through 


Onrille  Wright  and  Lieutmant  .S<-lfri<i(ff  In  tin-  Wright  Flyer,  built  for  the  U.  .S.   Army,  on  the  (hiy  of  the  trageily  which  cost 
the  Ufe  of  Lieutenant  Selfrldge,  who  was  the  first  man  to  be  killed  flying  in  an  aeroplane. 


THE  EVOLUTION  OF  MILITARY  AVIATION 


28» 


The  Langley  Aerodrome. 

Then  the  United  States  Government  commissioned  C.  P. 
Langley  to  construct  a  man-carrying  aerojilane.  The  "aero- 
drome" was  a  remarliable  advance  step,  but  the  experiments 
were  not  concluded. 

the  ordinary  military  acceptance  test  under  the 
following  conditions : 

(a )  The  test  consists  of  examination  of  work- 
manship and  materials,  speed  test,  fast  and  slow, 
climbing,  weight  of  load  carried,  rolling  test, 
and  one  hour's  flight.  The  constructor  must 
supply  the  pilot  and  passenger.  For  purposes 
of  calculation  weights  of  pilot  and  passenger 
will  be  160  lbs.  each. 

(b)  Stress  diagrams  in  duplicate  for  the  aero- 
plane must  be  sent  with  or  before  the  machine. 
A  minimum  factor  of  safety  of  6  throughout  is 
essential. 

(c)  No  machine  will  be  tested  for  military 
purposes  unless  it  fulfils  the  conditions  of  one  of 


the  types  used  for  military  purposes.     These 
are  given  in  attached  table. 

(d)  The  constructor,  when  applying  to  have 
his  machine  tested,  should  state  his  reasonable 
expectation  of  the  performances  of  the  ma- 
chine. 

(e)  Aeroplanes  submitted  for  test  must  be 
put  through  the  whole  of  the  test  unless  dam- 
aged before  their  completion,  or  unless  the 
Chief  Inspector  considers  that  the  test  should 
be  .stoi)i)ed  for  reasons  of  safety. 

2.  The  Chief  Inspector  of  Military  Aero- 
nautics is  also  prepared  to  examine  and  test 
aeroplanes  which  may  be  designed  not  for 
purely  military  purposes,  but  to  demonstrate 
some  practical  or  theoretical  improvement  in 
design  or  construction.  The  tests  imposed  in 
such  cases  will  be  at  the  discretion  of  the  Chief 
Inspector. 

3.  Results  of  any  test  will  be  supplied  ta 
the  constructor  by  the  Chief  Insi)ector,  and 
will  be  kept  secret,  if  desired  by  the  con- 
stioictor.  Should  the  constructor  wish  to  pub- 
lish the  result  of  the  test,  it  is  to  be  understood 
that  the  result  should  be  published  complete. 
Should  only  part  of  any  report  of  the  test  be 
published,  the  Chief  Inspector  reserves  the 
right  to  publish  it  in  full. 

4.  The  satisfactory  performance  of  the  tests, 
laid  down  in  paragraph  1  does  not  constitute  a 
guarantee  that  the  aeroplane  in  question  will  be 
purchased  by  Government. 

5.  These  tests  may  be  altered  from  time  to 
time ;  notice  will  be  given  as  early  as  possible  of 
any  alteration. 

War  Office, 

February,  1914. 


PERFORMAXCES  REQUIRED  FROM  VARIOUS  MILITARY  TYPES 

Tankage  to  give  an  en-         Light   Scout.           Reconnaissance                         Reconnaissance                                    Fighting  Fighting 

durance   of    Aeroplane  (a).                         Aeroplane    (6).                              Aeroplane    (a).  Aeroplane    (6). 

300  miles.                  300  miles.                 200  miles.  200  miles,  300  miles. 

To    carry     Pilot  only.                  Pilot  and  observ-    Pilot    and    observer,    plus    SO    lbs.  Pilot  and  gunntr.  plus  Pilot  and  gunner,  plus 

V                                             er,  plus  80  lbs.        for  wireless  equipment.                          300     lbs.      for     gun  100  lbs. 
for          wireless    35  to  60  m.p.h.                                             and    ammunition. 

equipment.             10  minutes.  45  to  do  m.p.h.  45  to  7S  m  p.h. 

45   to   75   m.ph,  10   minutes.  S  minutes. 

7  minutes,  A  clear  field  of  fire  in 

Range  of  speed   50  to  85   m.ph                                         To  land  over  a  30-ft.  vertical  ob-  A  clear  field  of  fire  in  every     direction    up 

To  climb  3500   feet  in    5   minutes.                                                          stacle  and  pull  up  within  a  dis-         every     direction     up  to  30°  from  the  line 

Miscellaneous  qualities    Capable   of   being                                            tance  of  100  yds,  from  that  ob-         to  30°  from  the  line  of  flight, 
started    by    the                                            stacle,  the  wind  not  being  more        of  flight, 
pilot         single-                                             than    15    m.p.h.     A    very    good 
handed.                                                           view  essential. 

Instructional  aeroplanes  with  an  endurance  of  150  miles  will   also  be  tested   under   special   conditions ;    safety   and   ease   of   handling  will   ba 

of   first   importance   in   this   type. 


240 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


The  Clement  Ader  Avion, 

In  1890-1897  the  French 
Government  planned  to 
construct  an  aerial  fleet 
and  enjraped  Clement 
Ader  to  do  it.  It  was 
the  first  time  a  jrovern- 
ment  had  actually  or- 
dered an  aeroplane  for 
military  use.  Ader's 
^vion  was  wrecked  in 
the  first  attempt  to  fly. 


Aeronautics  at  the  Outbreak  of  the  War 
Germany's  costly  failure  to  employ  aircraft 

IN  the  BELGIUM   INVASION 

Although  all  aeronautic  activities  in  Europe 
before  the  Great  War  were  of  a  military  na- 
ture, plans  for  the  employment  of  aircraft  for 
military  purposes  were  by  no  means  extensive. 
True,  the  largest  European  nations  had  be- 
tween 500  and  2000  aeroplanes  each,  and  some 
of  the  powers,  especially  Germany,  had  fleets 
of  dirigibles  and  some  observation  balloons. 
But  military  aeronautics  was  not  a  defined  sci- 
ence. Though  there  was  no  doubt  about  the 
value  of  aircraft  for  scouting  purposes,  and  an 


expectation  that  Zeppelins  could  do  awful  dam- 
age with  their  bombs,  the  general  application  of 
aircraft  for  military  purposes  was  mainly  a  mat- 
ter of  opinion.  While  some  of  the  aeronautic 
experts  were  good  prophets,  their  opinion  was 
questioned  by  thousands  of  people  who  con- 
sidered these  experts  visionaries.  Military  men 
of  the  old  school  were  slow  to  accept  the  value 
of  aircraft.  As  a  matter  of  fact,  the  Germans 
themselves  suffered  their  greatest  loss  through 
failure  to  recognize  the  value  of  aircraft  and 
through  failure  to  employ  them  in  their  initial 
campaign  against  Belgium. 

There  is  evidence  that  Germany  in  her  under- 
estimation of  the  tenacity  of  Belgium  did  not 
make  use  of  her  air  scouts  during  the  first  period 
of  her  campaign.     She  relied  entirely  on  the 


t)n<-  i)f  till'  iiirly    Kiismuti  .Mkcirslty  warplanes,  the  lirst  iiuuluiii-.s  Id  r:\ir\    nuilUjili-  power  plnlll^. 


THE  EVOLUTION  OF  MILITARY  AVIATION 


241 


overwhelming  strength  of  her  formidable  army, 
and  did  not  consider  it  necessary  to  employ  air 
scouts  to  find  vulnerable  spots  and  offset  the  ad- 
vantage gained  by  Belgium  through  the  latter's 
judicial  employment  of  the  able  Belgian  air 
scouts.  The  Germans  started  in  with  a  crush- 
ing preponderance  of  men,  but  played  the  game 
in  accordance  with  plans  made  many  years  ago, 
with  little  consideration  for  the  immediate 
moves  of  the  enemy.  Belgium,  with  few  men, 
but  employing  a  score  of  efficient  air  scouts, 
moved  as  circumstances  dictated.  The  i-esult 
was  a  comparatively  large  loss  of  men  and  in- 
estimable loss  of  time  on  the  part  of  the  Ger- 
mans. But  for  that  loss,  the  Germans  might 
have  gone  through  Belgium  and  on  to  Paris 
before  the  French  had  time  to  complete  their 
preparations. 

For  the  better  part  of  the  first  year  of  the 
war  aerial  operations  were  almost  entirely  con- 
fined to  scouting,  directing  artillery  fire,  and  an 
occasional  raid.  This  was  true  of  both  the 
heavier  and  lighter-than-air  craft. 

Then  a  logical  expansion  took  place.  Each 
side  tried  to  prevent  the  air  scouts  of  the  enemy 
from  reconnoitering  and  carrying  back  in- 
formation they  had  gathered;  also  to  prevent 
enemy  aircraft  from  dropping  bombs  over  their 
lines.  This  started  a  period  of  aerial  fighting, 
which  has  governed  the  supremacy  of  the  air 
ever  since. 

The  side  which  has  the  best  air  fighters  holds 
the  supremacy  of  the  air  on  the  fronts  and,  while 
able  to  get  information  about  every  movement 
of  the  enemy,  has  it  in  its  power  to  prevent  that 
enemy  from  obtaining  like  information.  Air 
superiority  may  be  said  to  be  responsible  for  all 
the  victories  on  the  different  fronts  in  the  pres- 
ent war. 

Next  came  the  famous  Boelke  and  Immel- 
man  with  their  high  horse-powered  Fokker 
monoi)lane,  merely  a  development  of  the  French 
Morane-Saulnier  monoplane,  equipped  with  a 
160  horse-power  engine.  Boelke  and  Immel- 
man  would  ascend  1.5,000  or  18,000  feet  and 
watch  for  an  opportunity  to  pounce  down  on  an 
enemy  aeroplane,  shooting  while  diving  down- 
ward. These  two  crack  German  aviators 
brought  down  a  number  of  Allied  aviators  be- 
fore the  Allied  commanders  realized  what  was 


happening.     Then  the  Allies  brought  out  their 
very  fast  machines. 

These  included  the  famous  Nieuport  biplanes 
and  Sopwith  speed  biplanes,  and  these  were 
quickly  followed  by  the  "Spads"  and  other  fast 
machines.  The  Allies  developed  a  great  many 
crack  aviators,  including  Lieutenants  Navarre, 
Guynemer,  William  Thaw,  Norman  Prince, 
Captain  Hall,  and  other  famous  aviators. 

A  new  development  came  with  the  employ- 
ment of  large  aeroplanes,  capable  of  carrying 
hundreds  of  pounds  of  explosives.  These  were  " 
used  by  both  sides  to  bombard  enemy  positions, 
and  made  it  necessary  for  each  side  to  be  ever- 
lastingly on  the  watch  to  protect  its  cities  and 
bases  from  aerial  attack,  thereby  withdrawing 
man}'  aviators  from  the  fronts.  But  the  num- 
ber of  aeroplanes  employed  was  always  too 
small  to  permit  achieving  decisive  victories 
through  reducing  positions  from  the  air. 

The  next  development  of  importance,  which 
took  place  in  1916,  was  the  employment  of  aero- 
planes to  perform  the  functions  of  cavalry,  in 
engaging  the  enemy  and  the  anti-aircraft  guns ; 
also  the  functions  of  the  artillery,  in  bombard- 
ing and  destroying  trains,  bridges,  and  bases; 
and  lastly  the  functions  of  the  infantry,  by  fly- 
ing low  and  attacking  troops  in  the  trenches  or 
along  roads. 

Advent  of  Large  Warplanes  in   1917  Per- 
mitted Conducting  Major  Aerial 
Operations 

The  advent  of  large  warplanes  in  1917  per- 
mitted conducting  major  aerial  operations. 
The  Italians  set  the  precedent  by  conducting 
numerous  air  raids  on  Austrian  bases  with  their 
large  Capi'oni  warplanes.  (See  chapter  on 
"Warplanes  for  Bombing  and  Launching  Tor- 
pedoes.") 

Russia  probably  could  have  done  the  same 
two  years  earlier  by  employing  the  large  Sy- 
korsky  aeroplanes,  but  the  Russian  Govern- 
ment did  not  have  the  organization  or  a  clear 
idea  of  the  value  of  the  large  warplanes,  and 
the  value  of  the  Sykorskj'  warplanes  was  lost  in 
a  succession  of  failures  due  to  lack  of  organiza- 
tion When  the  Sykorsky  machines  were  or- 
dered to  fly  to  the  front  from  their  base  hun- 


242 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


dreds  of  miles  away,  no  provision  was  made  for 
landing-places  along  the  route,  and  the  field 
from  which  they  were  to  operate  near  the  front 
was  not  suitable  for  large  machines.  The  re- 
sult was  that  only  two  machines  out  of  a  dozen 
survived  the  journey  from  the  home  base. 

As  the  Sykorsky  machines  were  slow,  they 
were  best  adapted  for  night  work,  but  there  was 
no  organization  for  work  of  this  nature.  There- 
fore the  machines  were  only  used  for  day 
operations,  and  in  this  style  of  fighting  they 
were  no  match  for  the  smaller,  but  faster  Ger- 
man machines.  Being  slow,  they  were  easy  tar- 
gets for  the  anti-aircraft  guns. 

The  Italians  began  with  a  very  efficient  or- 
ganization and  a  thorough  appreciation  of  the 
value  of  night  operations.  At  first  they  had 
only  a  small  number  of  machines,  but  as  fast  as 
they  could  build  more  they  increased  the  num- 
ber of  their  raiding  squadrons.  By  August, 
1917,  they  were  able  to  send  232  aeroplanes  in 
one  raid,  during  which  they  lost  only  one  aero- 
plane. 

The  United  States  Lagged  Behind  for 
Seven  Years 

After  gaining  the  distinction  of  owning  the 
first  military  aeroplane,  the  United  States  prac- 
tically stood  still,  while  other  nations  developed 
large  air  fleets.  From  the  time  the  first  aero- 
plane was  purchased  until  1916,  the  appropria- 
tion for  army  aeronautics  aggregated  only 
$600,000.  The  small  sums  allowed  each  year 
were  not  sufficient  to  support  even  one  manu- 
facturer, and  as  orders  were  distributed  among 
a  number  of  manufacturers,  and  the  recjuire- 
ments  for  aeroplanes  changed  with  each  order, 
the  aeroplane  manufacturers  did  business  with 
the  Government  at  a  loss.  During  this  period 
the  aeronautic  industry  was  kept  alive  mainly 
by  civilian  support  and  the  hope  of  better  times. 

In  1915-16  the  British  Ciovernment  placed 
substantial  orders  with  American  aeroplane 
manufacturers,  totalling  about  $13,000,000,  and 
thereby  developed  the  American  aeronautic  in- 
dustry. But  these  orders  were  entirely  for 
training  machines  and  sea-planes,  and  as  there 
was  no  demand  for  fast  fighting-machines  or 
large  lK)mbing-machines,  these  types  did  not  get 
beyond  the  experimental  stage. 


Aero  Club  of  America's  Monumental  Work 
in  Developing  Our  Aerial  Forces 

Throughout  these  lean  years  the  Aero  Club 
of  America  was  the  main  factor  in  developing 
our  aerial  forces.  This  patriotic  organization, 
which  has  fostered  the  development  of  aeronau- 
tics in  America  since  1905,  worked  incessantly  to 
build  up  the  air  service.  Through  energetic  ef- 
forts it  succeeded  in  having  appropriations  for 
military  aeronautics  increased,  and  trained,  or 
caused  to  be  trained,  several  hundred  militia 
and  civilian  aviators  who  later  became  aviators 
in  the  Aviation  Officers'  Reserve  Corps. 

In  1914-15  the  Aero  Club  of  America 
pointed  out  that  with  5000  aviators  this  coun- 
try would  be  in  the  position  of  the  porcupine, 
which  goes  about  its  daily  pursuits,  harms  no 
one,  but  is  ever  ready  to  defend  itself. 

When  the  63rd  Congress  appropriated  only 
$250,000  for  aeronautics  during  1915,  the  Aero 
Club  of  America  authorized  the  institution  of  a 
National  Aeroplane  Fund  to  develop  our  aerial 
defenses.  Some  idea  of  the  important  accom- 
plishments made  possible  by  this  fund  can  be 
gained  from  the  following  excerpts  from  the  re- 
port presented  to  the  Board  of  Governors  of  the 
club  by  Mr.  Alan  R.  Hawley,  chairman  of  the 
committee  which  had  charge  of  this  fund. 


America's  Entry  into  the  War  Brings  Deci- 
sion  to  Concentrate   Efforts   to   Strike 
Germany  Through  the  Air 

Following  America's  entry  into  the  war,  the 
Council  of  National  Defense  created  the  Air- 
craft Production  Board,  to  cooperate  with  the 
army  and  navy  to  increase  the  production  of  air- 
craft for  the  United  States,  as  well  as  for  the 
Allies. 

While  the  Aircraft  Production  Board  and 
the  military  authorities  were  considering  plans 
to  develop  a  substantial  air  sei-vice,  the  Aero 
Club  of  America  issued  a  series  of  statements 
pointing  out  that  an  additional  10,000  aviators 
would  make  it  possible  to  conduct  aerial  raids 
on  a  large  scale  and  to  strike  Germany  in  vital 
places, — to  strike  hard  enough  to  lead  to  per- 
manent victories.  It  recommended  the  appro- 
priation of  one  billion  dollars  to  carry  out  this 


THE  EVOLUTION  OF  MILITARY  AVIATION 


248 


plan  of  striking  Germany  through  the  air. 
Congiessman  Murray  Hulbert  of  New  York 
and  Senator  Morris  Sheppard  of  Texas,  who 
had  introduced  a  Bill  to  create  a  separate  de- 
partment of  aeronautics,  held  hearings  in  the 
Senate  at  which  authorities  testified  to  the  im- 
portance of  aeronautics. 

The  statements  of  the  Aero  Club  of  America 
and  other  authorities  were  published  daily  in  the 
press  for  about  one  month,  and  the  leading 
newspapers  also  sponsored  the  project  to  build 
large  air  fleets.  As  a  result,  practically  every 
paper  in  the  country  gave  editorial  support  to 
the  recommendations  for  a  large  appropriation 
for  aeronautics,  and  when  the  Bill  to  appropri- 
ate $640,000,000,  which  had  been  approved  by 
Secretary  Baker,  came  up  for  vote  in  the  House 
of  Representatives  on  July  14,  1917,  it  passed 
the  House  without  a  dissenting  vote.  The  Sen- 
ate passed  it  a  few  days  later. 

In  the  meantime,  the  Aircraft  Production 
Board  and  the  Signal  Corps  had  been  develop- 
ing plans  for  large  aviation  schools,  so  that  they 
were  ready  to  start  training  aviators  when  the 
appropriation  became  available. 

The   Problem   of   Delivering   Aeroplanes    to 
Europe 

The  one  serious  problem  is  the  delivery  of 
aeroplanes  to  Europe.  To  deliver  100,000 
aeroplanes  would  probably  take  most  of  the  ton- 
nage at  the  disposal  of  the  Allies,  to  the  exclu- 
sion of  practically  everything  else.  At  date  of 
writing  the  Aero  Club  of  America's  plan  to  fly 
the  machines  across  the  Atlantic  is  being  con- 
sidered. 

British  Air  Ministry  Created 

The  frequent  l)oinbing  raids  on  British  soil,  together  with  cer- 
tain very  evident  disadvantages  to  which  the  Allies  were  put 
through  Great  Britain's  failure  to  bomb  German  manufacturing 
centers,  destroying  German  bases,  railroads,  and  the  bridges  on 
the  Rhine,  caused  continuous  criticism  of  the  British  Govern- 
ment. This  criticism  became  very  severe  in  1916,  and  an  inves- 
tigation of  the  British  Flying  Corps  was  instituted,  which  lasted 
from  Ma.y  to  August.  As  a  result  of  this  investigation,  certain 
changes  were  made  in  the  management  of  the  Royal  Aircraft 
Factory,  and  then,  in  February,  1917,  the  Air  Board  was  created. 

The  members  of  the  Air  Board  were:  The  Right  Hon.  Vis- 
count Cowdray,  President;  Major  J.  I..  Baird,  C.  M.  G.,  D.  S.  ()., 
M.    P.,   Parliamentary   Secretary;    Commodore   Godfrey   Paine, 


C.  B.  .M.  \-.  C).,  R.  \.,  Director  of  Air  Service  (D.  S.  A.); 
Lieutcnant-General  Sir  David  Anderson,  K.  C.  B.;  Major-Gen- 
eral  J.  M.  Salmond,  C.  M.  G.,  D.  S.  O.,  Director  Cieneral  of 
Military  Aeronautics  (D.  G.  M.  A.);  Sir  William  Weir,  Con- 
troller of  Aeronautical  Supplies  (C.  A.  S.);  Mr.  Percy  Marin, 
Controller  of  Petrol  Engines  (C.  P.  E.). 

The  Air  Board  had  only  limited  power.  It  could  only  dis- 
cuss matters  of  i)olicy  in  relation  to  tlie  air  program  in  general, 
consider  the  programs  of  construction  of  aeroplanes  and  sea- 
planes formulated  by  the  Admiralty  and  the  War  Office,  and 
select  and  be  responsible  for  the  designs  of  aeroplanes  and 
seaplanes  and  their  engines  and  accessories. 

The  |)olicy  of  not  conducting  major  aerial  operations  against 
the  Germans  continued  with  the  new  Air  Board.  As  the  Ger- 
mans succeeded  in  maintaining  their  own  on  the  Western  front, 
at  the  same  time  striking  a  heavy  blow  at  Italy  and  Russia,  the 
criticisms  of  tlie  British  Govermnent  due  to  dissatisfaction  with 
the  management  of  aerial  matters  grew  more  and  more  severe. 
Decision  was  then  reached  to  establish  an  Air  Ministry.  Tliis 
was  done  in  November,  1017.  The  position  of  air  minister  was 
offered  by  Lloyd  George  to  Lord  Northcliffe,  who  declined  it. 
It  was  then  offered  to  Lord  Rothermere,  Lord  NorthcliiTe's 
brother,   who   accepted   it. 

The  Air  Council  of  the  Britisli  Air  Ministry  was  established 
on  January  2,  1918.     It  was  constituted  as  follows: 

Lord  Rothermere,  Secretary  of  State  and  President  of  the 
Council;  Major-General  Sir  H.  Trenchard,  K.  C.  B.,  D.  S.  ()., 
Chief  of  the' Air  Staff;  Rear-Admiral  Mark  Kerr,  C.  B.  R.  N., 
Dei)uty  Chief  of  the  Air  Staff;  Commodore  Godfrey  Paine, 
C.  B.,"  M.  V.  O.,  R.  N.,  Major-General  of  Personn<h  Major- 
General  W.  S.  Brancker,  Controllcr-Cieneral  of  Equijuncnt;  Sir 
William  Weir,  Director  General  of  Aircraft  Production  in  the 
Ministry  of  Munitions;  Sir  John  Hunter,  Adun'nistrator  of 
Works  "and  Buildings;  Major  J.  L.  Baird,  C.  M.  J.,  D.  S.  ()., 
M.  P.,  Parliamentary  lender-Secretary  of  State;  Lieutenant- 
General  Sir  David  Henderson,  K.  C.  B.,  D.  S.  O.,  Additional 
Member  of  Council  and  Vice-President. 

Mr.  W.  A.  Robinson,  C.  B.,  has  been  appointed  to  act  tem- 
porarily as  secretary  to  the  Council,  and  Mr.  H.  W.  McAually  to 
act  as  assistant  secretary. 

Sir  John  Hunter,  K.  B.  E.,  will  continue  to  perform  his  present 
duties  in  the  Ministry  of  Munitions,  in  addition  to  acting  as  Ad- 
ministrator of  Works  and  Buildings  in  the  Air  Ministry.' 

Tlie  German  drive  in  March-April,  1918,  emphasized  anew 
the  importance  of  aircraft  and  the  vital  necessity  of  nuiintain- 
ing  aerial  supremacy.  In  the  meantime  the  price  of  maintaining 
aerial  supremacy  had  increased.  Whereas  in  1910  it  took  only 
about  twenty  per  cent.  re))lacenients  of  aviators  and  fifty  per 
cent,  of  machines  per  month  to  keep  aero  squadrons  on  the  front, 
in  1918  it  took  over  doul)le  that  number.  This  was  due  to  higher 
skill  and  more  extensive  aerial  fighting;  increase  in  day  and 
night  bombing  at  low  altitudes;  increased  efficiency  of  anti-air- 
craft batteries,  firing  on  troops  from  low-flying  aeroplanes,  etc. 
In  other  word.s,  to  aim  to  keep  5000  aviators  on  the  fighting-lines 
for  the  year  1918-1919  involved  su]i|)lying  i?9,000  aviators,  re- 
quiring an  average  of  two  aeroplanes  each  to  train,  and  from 
60,000  to  70,000  machines. 

The  United  States  had  not  provided  for  such  an  expansion. 
Its  July,  1917,  plan  was  the  smallest  plan  that  could  be  adopted 
at  the  time  when  Italy  was  victorious  and  Russia  was  still  fight- 
ing. The  Senate  hearings  brought  out  the  fact  that  it  had  not 
been  changed  in  the  early  spring  of  1918,  when  the  Gei'inan 
drive  started. 


1  The  text  of  Act  Creating  British  Air  Ministry  is  to  be  founS 
in  Flying  (a  monthly  published  at  -29,0  Madison  Avenue,  New 
York  City  for  January,  1918.  The  text  of  the  first  estimates  of 
British  Air  Ministry  and  definition  of  duties  and  powers  of 
officials  of  the  Air  Ministry,  and  the  basis  of  cooperation  be- 
tween the  Air  Ministry  and  the  Admiralty  and  War  Office  ap- 
pear in  Flying  for  May,  1918. 


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844 


CHAPTER  XIX 


SOME  PROBLEMS  IN  AEROPLANE  CONSTRUCTION 

By  Capt.  V.  E.  Clark,  Chief  Aeronautic  Engineer,  United  States  Army;  Capt.  T.  F.  Dodd,  Signal  Corps, 

United  States  Army;  and  D.  E.  Strahlmann,  Engineer,  War  Department,  Office  of  the  Chief  Signal 

Officer.     (Paper  presented  January  1917  to  the  Society  of  Automotive  Engineers.) 

In  this  paper  we  shall  advance  for  discussion,  should  be  entirely  defenseless  against  the  attack 
with  hopes  of  solution,  some  important  problems  of  hostile  aeroplanes, 
connected  with  the  construction  of  aeroplanes 
intended  for  military  uses  in  the  United  States. 
Many  of  these  problems  also  apply  to  aero- 
planes built  for  commercial  and  sporting  pur- 
poses. Although  the  lessons  on  type  develop- 
ment that  are  being  learned  in  the  European 
war  are  of  immense  value  to  us,  many  conditions 
that  we  must  meet  are  peculiar  to  this  country. 


Military  Functions  of  Aeroplanes 

We  will  first  consider  the  various  military 
functions  (becoming  more  and  more  distinct), 
as  we  understand  them  at  present.  It  must  be 
borne  in  mind  that  other  important  uses  will,  in 
all  likelihood,   develop.     The   aeroplane   itself 


This  and  all  other  service  types  should  carry 
one  or  more  machine  guns,  and  the  general  ar- 
rangement of  the  system  should  be  such  as  to 
permit  extensive  fields  of  fire  in  important  direc- 
tions. 

The  useful  load,  that  is,  fuel  plus  the  military 
load,  and  the  speed  range,  determine  the  power 
required.  A  powerplant  of  about  200  h.p. 
would  apparently  satisfy  most  economically  this 
problem,  the  primary  requirements  of  the 
powerplant  being  reliability  and  fuel  efficiency. 

Assuming  this,  the  fuel  will  weigh  between 
700  and  800  lbs.  The  military  load  will  be  al- 
most 600  lbs.  The  complete  aeroplane,  fully 
loaded,  will  weigh  over  3,.500  lbs. 

This  aeroplane  would  also  be  adapted  for 


and  its  uses  in  war  are  so  new  that  it  is  impos-  long-distance  transportation  of  important  com- 
sible  to  predict,  with  any  degree  of  accuracy,  munications  or  officers, 
the  developments  in  even  a  few  months.  At 
present  the  aeroplane  is  being  used  in  war  for 
reconnaissance,  fire  control,  rapid  transporta- 
tion of  important  officers  or  communication,  de- 
molition of  valuable  structures  by  bombing,  and 
to  attack  hostile  aeroplanes  in  order  to  prevent 
them  from  performing  these  functions. 


la — STRATEGICAL-RECONNAISSANCE  MACHINES 

For  this  work  the  fuel  capacity  should  insure 
a  flight  of  at  least  500  miles  without  stop.  The 
average  speed  during  this  flight  should  not  be 
less  than  80  m.p.h.  The  military  load  consists 
of  one  pilot,  one  observer,  a  sketching  outfit,  a 
camera,  a  wireless  set,  and  navigating  instru- 
ments. 

The  general  rule  is  becoming  more  and  more 
firmly  established  that  no  military  aeroplane 


245 


lb — TACTICAL-RECONNAISSANCE    MACHINES 

The  fuel  capacity  of  this  type  should  insure  a 
continuous  flight  of  at  least  250  miles  at  a  speed 
of  not  less  than  85  m.p.h.  The  military  load 
should  be  about  the  same  as  that  carried  in  the 
strategical-reconnaissance  machine. 

A  powerplant  of  about  125  h.p.  is  desired, 
the  primary  requirement  being  reliability.  The 
fuel  will  weigh  about  225  lbs.,  the  aeroplane 
loaded  somewhat  less  than  2,400  lbs. 

2 — FIELD-ARTILLERY  FIRE-CONTROL 

The  tactical-reconnaissance  machine  can  per- 
haps perform  this  duty,  but  it  appears  that  the 
fire-control  machine  should  be  slower,  and  that 
one  of  its  primary  requirements  should  be  an 


246 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


extremely  good   field  of  vision.     The   engine 
should  be  of  125  h.p.,  or  perhaps  less. 

3 LOXG-KAXGER  BOMBERS 

We  here  attack  a  more  difficult  problem, 
owing  to  the  heavy  useful  load  with  which  we 
must  cHmb  from  the  starting  field. 

There  will  probabh^  be  a  wide  range  in  sizes 
of  machines  intended  for  this  duty.  We  will 
discuss  what  we  might  call  an  average  type  at 
the  present  time. 

The  fuel  capacity  should  permit  going  out  at 
least  200  miles  and  returning  safely,  starting 
with  a  load  of  bombs  weighing,  say,  400  lbs. 
The  machine  should  be  capable  of  defending  it- 
self from  hostile  aircraft,  so  that  it  can  operate 
independently  of  escort. 

It  appears  that  we  need  at  least  250  h.p.  and 
that,  depending  upon  the  total  useful  load,  300 
h.p.,  or  even  350,  would  not  be  too  great. 

If  we  assume  300  h.p.,  the  fuel  weight  will  be 
at  least  900  lbs.  and  the  total  military  load,  in- 
cluding bombs,  about  the  same. 

This  aeroplane  will  weigh,  loaded,  between 
5,000  and  6,000  lbs. 

4 — PURSUIT    MACHINES 

The  function  of  this  type  is  to  attack  and 
drive  off  hostile  aeroplanes  of  any  of  the  three 
first-mentioned  types,  preventing  them  from  ac- 
complishing their  purpose.  In  fact,  the  em- 
ployment of  this  type  should  afford  a  sort  of  of- 
fensive defense  against  hostile  aircraft  of  all 
descriptions. 

"While  the  types  la,  lb,  2  and  3  are  interested 
primarily  in  objects  on  the  ground,  the  pursuit 
type  is  occupied  solely  with  events  in  the  air. 
This  type  is  at  present  divided  into  the  one  and 
two-place  subclasses. 

a. — The  one-place  machine  carries  fuel  for 
two  hours  at  full  speed,  about  130  m.p.h.  The 
pilot  is  the  only  occupant.  He  controls  the  ma- 
chine and  operates  the  machine  gun,  or  guns,  of 
which  there  can  be  from  one  to  four.  He  usu- 
ally aims  the  gun,  in  action,  by  "pointing"  his 
aeroplane. 

All  characteristics  are  sacrificed  to  reason- 
able limits  in  order  to  obtain  rapid  climbing 
ability,  high  speed,  rapid  climbing  ability  at 


high  speed,  and  the  greatest  possible  dodging 
ability,  or  "handiness." 

In  the  engine,  reliability  must  be  sacrificed  to 
a  great  extent  to  obtain  low  weight  per  horse- 
power, in  order  that  the  necessary  attributes  of 
the  aeroplane  can  be  obtained.  Between  90 
and  130  h.p.  is  desired.  At  present  by  far  the 
greatest  percentage  of  engines  in  this  type  of 
machine  are  of  the  rotary  air-cooled  type. 

b. — The  tiico-place  machine  carries  fuel  for 
three  hours  at  full  speed,  about  110  m.p.h. 
Space  is  provided  for  two  men,  the  pilot  and  the 
gun  operator.  This  is,  of  course,  somewhat 
larger  and  less  agile  than  the  one-place  machine 
and,  it  is  believed,  is  rapidly  losing  its  popu- 
larity in  favor  of  the  smaller  type.  The  power 
required  is  from  110  to  160  h.p. 

5 — oat:rseas  reconnaissance 

a. — The  long-range  machine  of  this  type 
must  carry  fuel  for  six  hours  at  not  less  than 
75  m.p.h.  Two  men,  wireless-transmitting  set 
and  navigating  instruments  are  carried.  The 
300-h.p.  plant  used  on  the  bomber  should  an- 
swer for  this  t\'pe  satisfactorily,  the  greatest 
requirements  being  reliability  and  fuel  effi- 
ciency. 

b. — The  machine  used  for  short-range  recon- 
naissance and  coast-artillery  fire-control  must 
carry  fuel  for  three  to  four  hours  at  speed  of  not 
less  than  75  m.p.h.  Two  men,  navigating  in- 
struments, wireless  and  other  signaling  ajipa- 
ratus  will  be  required.  The  200-h.i:).  engine 
used  in  the  land  strategical-reconnaissance  ma- 
chine should  answer. 

Some  Problems  in  Construction 

It  is  important  that  engineers  work  out  the 
mechanical  details  of  a  gi-eat  many  problems  in 
construction,  among  which  are  the  two-propeller 
system,  the  reduction  of  vibration,  the  develop- 
ment of  light  engine  starters,  gasoline  supply 
systems,  devices  required  for  safe  landing  and 
improvements  in  wing  and  propeller  design. 

THE  TWO-PROPEEEER  SYSTEM 

"When  an  all-around  field  of  fire  is  necessary, 
the  best  arrangement  is  to  carry  the  two  or  three 


SOME  PROBLEMS  IN  AEROPLANE  CONSTRUCTION 


247 


operators  and  the  main  supply  of  gasoline  in  a 
central  body,  and  to  drive  the  machine  by  two 
propellers — one  at  each  side  of  this  central  body. 

By  such  an  arrangement  machine  guns  can  be 
fired  forward,  in  attack,  and  to  the  rear,  in  re- 
treat, with  extensive  fields  of  fire  in  both  direc- 
tions, above  and  below,  to  right  and  to  left. 
This  attribute  is  always  desirable,  and,  in  some 
types,  as  for  instance  in  the  bombers  and  recon- 
naissance machines,  is  essential. 

These  propellers  can  be  either  tractor  screws 
or  "pushers,"  The  left-hand  propeller  should 
turn  clockwise  and  the  right-hand  propeller 
counter-clockwise.  This  symmetrical  arrange- 
ment is  a  great  advantage,  in  that  it  permits 
equalized  torque  and  gyroscopic  efforts  when 
turning  in  different  directions.  In  addition,  it 
makes  for  safety,  because  the  downward  velocity 
imparted  to  the  inboard  parts  of  the  two  slip- 
streams that  strike  the  horizontal  tail-surfaces 
produces  an  inherent  tendency  toward  nose 
heaviness  without  power  and  toward  tail  heavi- 
ness with  power.  We  can,  therefore,  design  so 
that  the  line  of  thrust  is  considerably  above  the 
center  of  gravity,  compensating  for  this,  and 
obtaining  another  convenient  feature. 

A  fourth  great  advantage  of  such  a  system  is 
the  fact  that  great  power  can  be  transmitted 
with  good  propeller  efficiency  without  demand- 
ing excessive  diameter  and  retaining  satisfac- 
tory structural  safety  factors.  It  is  highly  de- 
sirable that  the  line  of  thrust  of  the  propeller  be 
kept  below  the  center  of  gravity  of  the  aero- 
plane, unless  the  two-propeller  arrangement,  as 
described  above,  be  used;  a  propeller  of  large 
diameter,  with  sufficient  clearance,  necessitates 
a  high  landing  gear  with  its  many  great  disad- 
vantages. It  appears  extremely  difficult  to 
build  a  propeller  of  wood,  of  satisfactory 
strength  (if  the  speed  of  revolution  be  high), 
giving  good  efficiency,  to  transmit  more  than 
160  h.p.  Peculiarly  stringent  climatic  condi- 
tions making  for  rapid  deterioration  have  in- 
creased this  difficulty.  In  fact  the  tendency  to 
reduce  cylinder  diameter  and  increase  crank- 
shaft revolution  speed  is  already  necessitating  a 
gear  between  crankshaft  and  propeller-shaft  in 
order  to  keep  the  propeller  speed  below  1,300 
r.p.m.,  which  is  considered  desirable. 


A  fifth  advantage  of  the  two-propeller  ar- 
rangement is  that  the  total  resistance  of  the  air 
to  progress  through  it  of  the  complete  aeroplane 
while  flying  under  power  will  be  diminished 
owing  to  the  fact  that  less  total  projected  area 
of  bodies  will  lie  in  the  propeller  slip-streams. 
The  velocity  of  the  air  striking  objects  lying  in 
the  slip  stream  is,  say,  20  per  cent,  higher  than 
the  velocity  of  air  not  in  the  slip  stream.  The 
resistance  varies  about  as  the  square  of  the 
velocity.  Therefore,  all  other  things  being 
equal,  less  power  will  be  required  to  overcome 
the  total  resistance. 

ARRANGEMENTS    WITH    TWO    PROPELLERS 

Four  different  systems  for  two-propeller  in- 
stallation have  been  suggested: 

1.  Two  engines,  one  on  each  side,  mounted 
out  on  the  wings.  The  fundamental  weakness 
of  this  system  is  that  these  great  masses,  re- 
moved so  far  from  the  center  of  gravity  of  the 
aeroplane,  produce  great  moments  of  inertia, 
and  consequently  slow  periods  of  oscillation. 
The  machine  is  "logy"  and  probably  not  satis- 
factory for  any  but  "hydro"  purposes,  in  which 
case  a  "snappy"  machine  is  impossible  at  best. 

2.  Two  engines  mounted  in  the  central  body 
between  pilot  and  observer,  each  driving  its  own 
pi'opeller  through  bevel  gears  and  shafts,  or  by 
other  method,  the  two  systems  being  independ- 
ent. 

3.  One  large  engine,  mounted  in  the  central 
body,  driving  both  propellers,  one  propeller  at 
each  side. 

4.  Two  engines,  mounted  in  the  central  body, 
with  a  system  of  clutches  connected  with  the 
transmission  system  in  such  a  manner  that  either 
engine,  or  both  engines,  can  drive  both  pro- 
pellers, it  being  possible  for  the  pilot  to  shift 
during  flight. 

The  last  system  presents  many  advantages 
over  the  others,  but  it  is  entirely  possible  that 
excessive  weight  and  complexity  will  render  it 
impracticable.  The  system,  as  a  whole,  must 
be  reliable. 

In  the  design  of  any  system  of  transmission 
for  the  two-propeller  arrangement,  the  en- 
gineer must  bear  in  mind  that  the  structure  of 
the  wings  supporting  the  propeller  and  trans- 


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mission  is  very  light  and  rather  flexible,  usually 
vibrating  during  flight. 

The  information  at  hand  indicates  that,  to 
date,  no  successful  aeroplane  of  the  two-pro- 
peller type  has  been  developed,  but  it  is  urged 
that  the  possible  advantages  are  such  as  to  war- 
rant great  effort  on  the  part  of  engineers  to- 
ward this  improvement. 

METHODS  OF  REDUCING  VIBRATION 

The  problem  of  reducing  vibration  of  the 
aeroplane  in  flight,  initiated  by  the  engine,  is  a 
serious  one.  It  is  difficult  to  realize,  without 
actual  experience,  the  viciousness  of  this  vibra- 
tion, especially  when  the  engine  is  of  the  eight- 
cylinder  type,  even  though  it  is  running  nor- 
mally. After  one  experiences  this  vibration,  it 
is  easy  to  understand  why  ignition  systems, 
gasoline-supply  joints,  water-cooling  systems, 
delicate  instruments,  and  even  wire  terminals 
and  structural  joints  of  the  aeroplane  itself,  de- 
teriorate so  rapidly. 

The  vibration  throughout  the  aeroplane  can 
of  course  be  reduced  by  better  design  of  the  en- 
gine mounting,  but  we  cannot  hope  to  eliminate 
it  entirely  in  this  manner,  if  the  engine  itself  is 
not  of  the  proper  design.  We  must  not,  in  this 
connection,  get  the  idea  that  the  engine  is  al- 
ways operating  at  the  same  speed  during  flight. 
We  can,  for  instance,  if  flying  at  extremely  high 
speed,  turn  the  crankshaft  over  at,  say  2,000 
r.p.m.;  whereas,  if  our  sole  object  is  to  remain 
in  the  air  without  losing  altitude,  as  when  spot- 
ting for  artillery  fire,  we  can  use  a  crankshaft 
speed  of,  say,  not  more  than  1,200  r.p.m.  The 
vibration  at  any  speed  should  not  be  excess- 
ive. 

STARTING    MOTOR   FOR   ENGINES 

The  development  of  light  starters  is  a  matter 
of  immediate  importance.  For  instance,  a  sea- 
plane cfjuipped  with  two  engines,  one  out  on 
each  wing,  would  be  utterly  useless  without  re- 
liable starters.  It  seems  quite  probable  that 
electric  starters  will  be  preferable,  if  the  weight 
can  he  reduced  sufficiently,  and  if  the  danger  of 
spilling  electrolyte  be  eliminated.  It  appears 
that  any  engine  of  over  140  h.p.  requires  a 
starter. 


Reliable  provision  for  starting  the  engine  in 
extremely  cold  weather  is  necessary. 

GASOLINE   SUPPLY-SYSTEM 

To  date  none  of  our  pilots  is  anxious  to  fly 
across  country  with  any  except  gravity  feed. 

The  gasoline  supply-systems  Figs.  1  and  2, 
required  by  the  U.  S.  Army  for  twin-engine 
seaplanes,  is  as  follows: 

The  flow  of  fuel  shall  be  from  the  main  sup- 
ply tank  in  central  bodj^  to  the  gravity  service- 
tank  located  at  the  center  of  the  upper  wing; 
from  gravity  service-tank  by  gravity,  along  the 
lower  wing  panels,  to  the  small  headers  at  the 
carbureters  of  the  two  engines,  and  from  the 
small  headers  in  each  case  to  the  carbureter. 

These  tanks  shall  have  fuel  capacities  suf- 
ficient for  operation  at  full  rated  power,  as  fol- 
lows :  Main  supply  tank,  4  hr.  3.5  min. ;  gravity 
service-tank,  25  min. ;  each  header  to  carbureter, 
1  min. 

The  design  and  material  of  the  gasoline  sup- 
ply-system throughout  shall  be  such  as  to  ob- 
tain extreme  lightness  as  far  as  consistent  with 
strength  and  resistance  to  corrosion. 

MAIN  GASOLINE-SUPPLY  TANK  IN  CENTR^VL  BODY 

This  shall  be  divided  by  one  vertical  longitu- 
dinal bulkhead  and  one  vertical  transverse  bulk- 


To"k  fv  Cariurtfr^S 


'*(]-Ofi 


RFT^P^ 


Fig.   1 — Gasoline  supply  system    (suction   pump)    for   military 
seaplane 

head  into  four  gasoline-tight  compartments. 
Proper  swash-baffle  plates  shall  bo  installed. 
The  tank  shall  be  of  sturdy  construction 
throughout. 

The  main  tank  shall  be  of  such  shape  as  to 


SOME  PROBLEMS  IN  AEROPLANE  CONSTRUCTION 


249 


properly  fit  the  central  body.  It  shall  be  se- 
curely fastened  in  the  structure  of  the  central 
body  in  such  a  way  as  to  be  undisturbed  by  any 
possible  motion  of  the  aeroplane.  The  struc- 
ture shall  be  such  that  the  tank  will  withstand 
an  internal  pressure  of  at  least  7  lbs.  per  sq.  in. 
without  leakage  of  gasoline.  The  design  shall 
be  such  that  there  will  be  no  ill  effects  from 
drumhead  vibration. 

Suitable  means  shall  be  provided  for  quickly 
and  conveniently  filling  and  for  completely 
draining  all  four  compartments. 

Each  filling  hole  shall  have  a  suitable  screen 
filter,  100  mesh  to  the  inch. 

Plugs  or  caps  for  filling  holes  shall  be  air- 
tight and  provision  shall  be  made  for  "safety- 
ing"  them  positively  in  place.  Suitable  gaskets 
shall  be  used. 

Provision  for  reducing  to  a  minimum  the  rate 
of  leakage  due  to  bullet  holes  by  lining  the  in- 
side of  the  tank  with  a  special  material,  is 
highly  desirable. 

Suitable  gasoline-supply  gage  shall  be  in- 
stalled. 

There  shall  be  leads  from  the  bottoms  of  the 
four  compartments  to  the  upper  gravity  serv- 
ice-tank. 

SUPPLY   OF   GASOLINE   FROM    MAIN    TO   GRAVITY- 
SERVICE  TANK 

This  shall  be  by  two  methods : 

First. — Air  fan  driven  pump,  so  designed  as 
to  maintain  proper  air  pressure  in  or  suction 
from  the  main  tank  system,  and  to  operate  satis- 
factorily during  flight.  An  alternative  and  bet- 
ter method  will  be  to  install  two  such  fans,  each 
fan  maintaining  pressure  in  any  two  of  the 
four  compartments  of  the  main  tank.  When 
any  one  or  two  of  the  four  compartments  of  the 
main  tank  leaks  (because  of  bullet  hole  or 
through  other  cause) ,  an  arrangement  by  which 
pressure  or  suction  can  be  maintained  through 
the  leads  from  the  tight  compartments  is  highly 
desirable. 

Second. — A  hand  air-pressure  pump  in  or  at 
the  side  of  the  pilot's  cockpit,  which  can  be  used 
when  not  in  flight  or  in  an  emergency.  This 
pump  shall  be  located  in  the  cockpit  at  a  point 
as  high  as  will  permit  convenient  operation  by 


the  pilot  in  his  seat.  It  shall  be  provided  with 
a  suitable  air-pressure  gage,  visible  to  the  pilot. 
Its  connections  with  the  compartments  of  the 
main  tank  shall  be  at  a  point  as  high  as  prac- 
ticable to  prevent  the  pump  becoming  flooded 


<^>{>ft 


f3F7 


Fig.  2 — Gasoline  supply  system  (air  pressure)  for  military  sea- 
plane 

with  gasoline.  An  arrangement  by  which  pres- 
sure can  be  maintained  by  the  hand  air-pressure 
pump  on  tight  compartments  of  the  main  tank 
when  one  or  two  compartments  leak  is  highly  de- 
sirable. 

CONSTRUCTION  OF  GRAVITY  SERVICE-TANK 

This  tank  shall  be  of  sturdy  construction,  se- 
curely supported  in  place,  and  provided  with  the 
proper  number  of  swash-baffle  plates.  It  is 
considered  desirable  to  protect  this  tank. with 
light  V-shaped  armor  on  the  under  side. 

An  automatic  ball-float  valve  shall  be  pro- 
vided to  prevent  overfilling  of  this  tank.  A 
suitable  overflow  pipe  out  of  the  top  center  of 
the  gravity  service-tank  shall  be  provided.  The 
gravity  service-tank  shall  be  of  good  stream-line 
form. 

A  suitable  gage,  visible  to  the  pilot  in  his 
seat,  shall  be  in  the  gravity  service-tank.  This 
gage  shall  be  connected  at  such  a  point  that  it 
will  register  accurately  through  the  range  of 
normal  flight  attitudes. 

From  the  gravity  service-tank  the  gasoline 
shall  be  led  to  a  small  header  at  each  engine  by 
leads  within  or  along  the  lower  wing  panels. 
Between  gravity  service-tank  and  each  header 
shall  be  two  independent,  and,  as  far  as  prac- 
ticable, isolated  tube  leads.     Each  of  these  four 


250 


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leads  shall  connect  with  the  lower  part  of  the 
gravity  sen'ice-tank  at  such  a  point  that  the 
supply  will  not  be  interrupted  at  any  normal 
flight  attitude. 

At  the  connection  of  lead  to  the  gravity  serv- 
ice-tank shall  be  a  suitable  wire  gauze  strainer, 
mesh  100  to  the  inch.  Provision  shall  be  made 
to  prevent  the  possibility  of  air  pockets  in  the 
gasoline  leads  from  the  gravity  service-tank. 
Provision  shall  be  made  for  permitting  the  pilot, 
while  in  his  seat,  to  cut  off  the  gasoline  supply, 
through  all  leads,  from  the  gravity  service-tank 
to  the  carbureter  headers. 

HEADERS    BETWEEN    CARBURETEE    AND    SERVICE- 
TANK 

A  small  cylindrical  or  stream-line  tank  or 
header  shall  be  installed  in  the  immediate 
vicinity  of  each  carbureter.  The  gasoline  shall 
pass  through  this  header  after  coming  from  the 
gravity  service-tank. 

Its  capacity  shall  be  sufficient  for  one  min- 
ute's running  at  full-rated  horsepower.  The 
central  portion  of  this  header  shall  be  on  a  level 
with  the  jets  of  the  carbureter.  The  axis  of  the 
cylinder  shall  be  vertical. 

The  cylinder  shall  be  of  sufficient  length  to 
give  satisfactory  head,  either  when  the  aero- 
plane is  in  normal  attitudes  or  when  it  is  upside 
■down. 

Provision  shall  be  made  to  prevent  gasoline 
from  backing  up  into  the  service  lead  instead  of 
coming  into  the  carbureter  when  the  engine  is 
upside  down. 

Suitable  gasoline  cutoff  shall  be  installed  near 
this  header  in  such  a  position  as  to  be  convenient 
for  operation  to  a  man  standing  on  the  ground 
or  on  the  wing. 

TUBING   FOE   FUEL   LEADS 

At  every  point  these  shall  be  of  the  highest 
grade  material  best  suited  for  the  purpose.  It 
shall  he  approved  by  the  inspection  department. 
Flexible  tubing  shall  be  ^e-in.  No,  2  copper 
tubing.  Non-flexible  leads  shall  be  piping  as 
approved  by  the  inspection  department. 

Tubing  .shall  in  all  cases  be  of  diameter  suffi- 
cient to  give  free  and  continuous  flow  under  se- 


vere vibratory  conditions.  In  the  absence  of 
other  instructions  the  bore  shall  be  %6-in. 

All  tubing  shall  be  securely  fastened  in  such 
a  way  as  to  resist  wear,  vibration,  and  chafing. 
The  number  of  joints  and  fittings  shall  be  re- 
duced to  a  minimum. 

Unions,  ells,  tees,  and  fittings,  to  be  S.  A.  E. 
standard,  approved  by  the  inspection  depart- 
ment. The  method  of  connecting  all  leads  shall 
be  aj^proved  by  the  inspection  department.  All 
fittings  shall  be  readily  accessible  for  inspection, 
adjustment,  repair,  or  removal. 

It  will  be  seen  that  it  will  require  consider- 
able ingenuity  to  work  out  satisfactorily  the  me- 
chanical details  of  this  complicated  arrange- 
ment. For  instance,  a  satisfactory  method  of 
insuring  feed  from  the  compartments  of  the 
main  tank,  up  to  the  gravity  tank,  when  one  or 
more  of  the  main  compartments  are  punctured 
by  shot,  is  required. 

MET^VL    CONSTRUCTION    FOR    AEROPLANES 

It  is  suggested  that  the  field  for  development 
of  steel  aluminum  alloy  in  the  structure  of  aero- 
planes is  one  offering  considerable  inducement. 
The  authors  have  gone  briefly  through  the  lay- 
out of  an  aeroplane  in  which  every  strength 
member  is  of  metal.  In  this  design  it  was 
found  most  convenient  to  use  seamless  steel  tube 
at  some  places,  welded  tube  at  others,  channel 
section  at  others,  I-section  and  L-section,  at 
others.  At  a  few  points  aluminum  alloy  was 
used,  at  other  points  pure  aluminum,  assump- 
tion being  made  that  this  aluminum  was  rolled 
in  such  a  way  as  to  give  it  certain  desired  phj'si- 
cal  characteristics. 

It  is  suggested  that,  even  with  the  present 
standard  method  of  construction,  there  is  great 
room  for  improvement  in  the  material  and 
method  of  heat  treatment  of  the  metal  fittings 
used  in  conjunction  with  wood  and  wire.  Es- 
pecially where  fittings  are  bent  both  with  and 
across  the  grain,  a  special  alloy  appears  advis- 
able. The  same  holds  for  fittings  shaped  by 
die-forging.  Chrome  vanadium  steel,  to  com- 
ply with  S.  A.  E.  specifications  6130,  and  heat 
treated  in  such  a  way  as  to  render  it  best  in  each 
case,  is  suggested.  It  is  believed  that  the  total 
weight  of  an  aeroplane  can  be  materially  de- 


SOME  PROBLEMS  IN  AEROPLANE  CONSTRUCTION 


251 


creased,  without  sacrifice  of  strength,  and  hence 
superior  performance  obtained,  by  the  use  of 
better  steel. 

The  construction  of  floats  of  metal  for  sea- 
planes appears  to  be  a  possibility  as  is  also  the 
use  of  metal  for  aeroplane  propellers.  It  is 
possible  that  the  entire  body  might  be  made  of 
light  pressed  steel,  or  aluminum,  with  holes  to 
decrease  the  weight  cut  at  proper  places,  and 
covered  with  linen. 

ri,EXIBLE    PIPING 

Satisfactory  flexible  gasoline  lead  has  not  yet 
been  developed.  Such  a  lead  should  resist  the 
action  of  vibration,  should  be  light  in  weight  and 
resist  cutting  or  denting.  The  method  of  mak- 
ing joints  is  important.  The  duct  should  be 
carefully  sweated  into  proper  terminal  fittings. 
Tube  ends  of  fittings  should  have  spiral  springs 
wound  around  them  for  at  least  2/4  in.,  thus  pre- 
venting sharp  bends  and  disturbing  the  effects 
of  vibration.  All  unions  should  be  ground, 
with  spherical  seats,  and  threads  should  be  cut 
clear  and  sharp,  with  all  burrs  removed.  The 
inside  diameter  of  tube  should  not  be  less  than 
0.35  in. 

A  flexible  pipe,  light  in  weight,  of  material 
suitable  for  leading  the  exhaust  away  from  the 
engine  would  be  useful. 

MUFFLER   REQUIREMENTS 

In  military  service  a  hostile  aeroplane  is 
usually  first  discovered  by  hearing  it.  A  muf- 
fler satisfactory  as  to  low  weight,  flexibility,  loss 
of  power  through  back  pressure,  durability 
against  corrosion,  and  efficiency  as  a  muffler,  is 
highly  desirable. 

SHOCK   ABSORBERS   FOR   LANDING   GEAR 

Rubber  is  not  satisfactory  as  a  shock  absorber 
for  heavy  aeroplanes.  Neither  is  it  satisfactory 
as  a  military  supply,  especially  when  it  is  sub- 
jected to  heat  and  the  direct  rays  of  the  sun. 
It  seems  necessary  to  develop  a  steel-spring 
shock-absorber.  The  action  of  this  steel  spring 
must,  however,  be  damped  by  an  oil  cylinder. 
Without  this  damping  the  action  is  such  as  to 
cause  the  aeroplane  to  bound  excessively  upon 
striking  the  ground. 


BRAKES    REQUIRED    WHEN    LANDING 

The  development  of  a  brake  to  reduce  the  run 
of  the  aeroplane  after  it  has  touched  the  ground, 
thus  permitting  it  to  land  in  restricted  areas, 
appears  to  be  a  difficult  problem.  It  is  a  moot 
question  whether  such  a  brake  is  desirable  when 
the  simple  two-wheel  landing  gear  is  used,  as  its 
action  has  a  tendency  to  throw  the  aeroplane 
over  on  its  nose.  Where  more  than  two  wheels 
are  used,  however,  a  brake  fitted  to  the  two  main 
rear  outside  wheels  in  such  a  way  that  the  pilot 
can,  from  his  seat,  operate  either  brake,  or  both 
brakes  together,  would  be  desirable.  Such  an 
arrangement  would  permit  him  not  only  to  stop 
his  machine  quickly,  but  also  to  steer  it  on  the 
ground  to  some  extent. 

FOLDING   LANDING   GEAR 

The  development  of  a  landing  gear  that  can 
be  submerged  within  the  body  by  the  pilot,  dur- 
ing flight,  would  materially  increase  the  speed 
of  the  aeroplane  by  reducing  the  "parasite"  re- 
sistance. Such  a  mechanism  should  be  light  in 
weight,  sturdy  and  simple. 

GASOLINE   SUPPLY   GAGE 

The  development  of  a  gage  to  indicate  the 
supply  of  gasoline  remaining  in  the  tanks  to 
the  pilot,  whose  seat  can  be  out  of  view  of  the 
tanks,  is  necessary.  Such  a  gage  should  be 
simple  and  sturdy.  The  accuracy  and  re- 
liability with  which  it  registers  should  not  be 
affected  by  any  change  in  altitude  of  the  aero- 
plane. It  should  not  form  a  possible  source  of 
leakage.  It  should  be  adapted  to  both  the  pres- 
sure and  suction  systems  of  feed. 

FIRE   SAFETY-DEVICE 

Many  casualties  have  occurred  because  the 
aeroplanes  have  caught  fire  in  the  air.  While 
it  has  been  impossible  to  determine  from  the 
wreck  just  what  led  to  the  fire,  it  is  quite  prob- 
able that  many  of  these  accidents  were  due  to 
back  fire  into  the  carbureter  that  forced  burn- 
ing gasoline  out  into  the  surrounding  structure, 
or  to  a  leaking  gasoline  tank.  The  develop- 
ment of  a  device  that  will  render  such  an  acci- 
dent impossible  would  save  many  lives. 


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In  this  connection  it  should  always  be  a  rule 
for  aeroplane  constructors  never  to  have  any 
electric  lead  near  a  gasoline  supply  or  lead. 

ALTITUDE   ADJUSTMENT   FOR   A   CARBURETER 

The  development  of  a  device  to  regulate  auto- 
matically the  mixture  for  variations  in  density 
of  air  incident  to  changes  in  altitude,  would  be 
valuable. 

VIBRATIOX-ABSORBING    MATERIAL 

The  development  of  a  material  more  suitable 
than  ordinary  felt  for  padding  the  points  of 
support  of  radiators,  and  the  like,  is  highly  de- 
sirable. 

VARIABLE   RADIATORS 

A  more  suitable  method  of  permitting  the 
pilot  to  adjust  the  amount  of  cooling  done  by 
the  radiator  in  order  to  compensate  for  changes 
in  temperature  of  air,  or  changes  in  speed 
through  the  air,  is  necessary.  Such  arrange- 
ment should  permit  operation  by  the  pilot  from 
his  seat  during  flight,  or,  better  yet,  might  be 
automatic ;  the  device  being  operated  as  a  func- 
tion of  the  temperature  of  the  water.  It 
should  be  durable  and  should  act  with  reliability. 

VARIABLE-CAMBER   AVING 

Great  speed  range  is  a  desirable  attribute  of 
an  aeroplane,  as  it  permits  high  speed  of  travel 
in  the  air  and  yet  low  speed  while  landing,  which 
of  course  makes  for  safety  if  the  landing  place 
be  small  or  rough.  Great  improvement  in  the 
speed  range  can  be  brought  about  by  use  of  a 
variable-camber  wing  surface,  that  is  to  say,  if 
the  section  form  of  the  aerofoil  could  be  changed 
at  will  during  flight  from  a  shape  such  as  A  to 
one  similar  to  B,  Fig.  3. 


tive  wind).  At  small  angles  of  attack,  where 
the  lift  coefficient  is  low,  this  shape  has  a  rela- 
tively high  resistance  and  will  consequently  re- 
quire a  gi'eat  power  to  drive  it  through  the  air 
at  speed  high  enough  for  the  necessary  support. 

The  reverse  is  true  of  such  a  shape  as  A, 
which,  though  the  lift  coefficient  is  poor,  has  an 
appreciably  lower  resistance  or  "drag." 

If,  then,  we  could  utilize  the  section  B  for 
slow  speed,  as  in  making  landings,  and  section 
A  for  high  speed,  the  safe  limits  of  speed  be- 
tween which  the  aeroplane  could  fly  would  be 
extended.  The  variable-camber  would  permit 
changing  the  characteristics  of  the  wing  to  suit 
conditions. 

Performance  curves    (Figs.  4  and  5)   have 


Fig.  3 — Variable  forms  of  aerofoil  sections 

An  aerofoil  such  as  shown  in  B,  has  a  high 
lift  coefficient  at  large  angles  of  attack  (the 
angle  of  attack  being  the  angle  between  the 
chord  tangent  to  the  lower  surface  and  the  rela- 


SP£ED  MILCS  PER  HOUR 

Fig.  4 — Performance  curves  for  aeroplane  with  ftxed-camber  wing 

been  worked  out  for  a  pursuit  machine  having  a 
good  aerofoil  (ffxed-camber)  in  common  use  to- 
day ;  and  a  similar  series  of  curves  for  a  machine 
with  an  assumed  variable-camber  wing.  It  has 
been  assumed  that  otherwise  both  aeroplanes 
are  similar.  No  allowance  has  been  made  for 
the  probable  increase  in  weight  of  the  variable- 
camber  machine  due  to  the  operating  mechanism 
and  structure. 

The  slow  speed  of  the  fixed-cambered  wing 
aeroplane  is  61  m.p.h.  This  will  only  permit 
landing  the  aeroplane  on  an  ideal  field  by  a  very 
skilful  pilot. 

On  the  other  hand  the  variable-cambered  wing 
aeroplane  can  be  flown  at  a  slow  speed  of  56 
m.p.h. 

The  curves  show  that  with  the  variable  cam- 
ber a  higher  speed,  127  m.p.h.,  as  against  120 
for  the  fixed  camber,  can  be  obtained  with  the 


SOME  PROBLEMS  IN  AEROPLANE  CONSTRUCTION 


253 


same  power.     The  same  speed  might  be  ob- 
tained with  less  power. 


SPEED    MILES  PER  HOWR 

Fig.  S — Performance  curves  for  aeroplane  with  variable-camber 

wing 

//  the  same  high  speed  were  desired  the  vari- 
able-camber wing  might  have  a  greater  area. 
It  would  then  have  a  slow  speed  of  46  m.p.h.  as 
against  61  for  the  fixed  camber  (allowing  for 
increased  weight  due  to  added  surface),  which 
would  permit  its  being  flown  and  being  landed 
in  an  ordinary  field,  by  the  ordinarily  skilful 
pilot. 

It  can,  therefore,  be  seen  that  the  invention  of 
a  suitable  variable-cambered  wing  would  be  a 
big  step  in  advance. 

APPENDIX 

In  calculating  the  values  used  in  plotting  the 
performance  curves.  Figs.  4  and  5,  the  weight 
of  machine  was  assumed  as  1150  lbs.,  and  the 
engine  was  assumed  to  develop  140  b.h.p. 

The  lifting  power  of  a  wing  is  given  hy  L  = 
KvA  V^,  where  L  is  the  lift,  Kv  the  lift  coefficient 
(which  varies  for  different  altitudes  of  the  wing 
to  the  relative  wind  and  must  be  determined  by 
experiment),  A  is  the  area  of  the  wings  and  V 
the  air  speed. 

Similarly  the  resistance  of  a  wing  is  expressed 
by  D  =  K):A  V^,  Kx  being  a  variable  coefficient 
that  must  be  found  by  experiment. 

The  speed  at  which  the  aeroplane  must  fly  for 
any  assumed  angle  of  attack  can  be  found  from 
the  lift  formula.  The  lift  in  all  cases,  of  course, 
is  assumed  to  be  the  weight  of  the  aeroplane. 

The  resistance  of  the  wings  at  these  speeds 
can  then  be  determined  and  the  total  resistance 


found  by  adding  the  parasite  resistance,  that  is, 
the  resistance  of  the  body,  landing  gear,  etc. 

From  the  total  resistance  the  horsepower  re- 
quired can  be  calculated  and  plotted  against 
speed.  The  horsepower  available  is  obtained 
by  multiplying  the  efficiency  of  the  propeller  by 
the  brake  horsepower  delivered  by  the  engine. 


I  SECTION 

Fig.  6 — Rib  used  in  present  type  of  wing  construction 

The  ribs  as  ordinarily  used  in  the  present 
type  of  wing  construction  are  as  shown  in  Fig. 
6.  The  weight  of  such  a  rib  for  a  small  pur- 
suit machine,  as  assumed  in  the  above  calcula- 
tions would  be  less  than  I/2  lb.  The  ribs  would 
be  spaced  from  12  to  15  in.  along  the  spars.  A 
wing  complete  with  cover,  internal  bracing,  etc., 
weighs  from  0.6  to  0.7  lb. 

PKOPELI,ERS   WITH    VARIABLE-PITCH   ANGLE 

Improved  performance  of  an  aeroplane,  espe- 
cially as  regards  radius  of  action,  can  be  brought 
about  by  means  of  a  propeller  whose  pitch  angle 
can  be  varied  by  the  pilot  while  in  flight.  The 
liability  of  failure,  the  complexity  of  the  mecha- 
nism and  the  weight  added,  must  be  weighed 
against  the  gain  obtained  in  the  performance. 

The  gain  in  efficiency  of  the  variable-pitch 
propeller  over  the  fixed-blade  type  is  consider- 
able. This  increased  efficiency  makes  available 
more  horsepower  for  climbing,  giving  faster 
climbing,  and  permits  throttling  down  to  attain 
the  economical  speed,  and  hence  increases  the 
flight  radius  and  the  time  in  the  air  with  a  given 
quantity  of  fuel. 

These  facts  are  more  clearly  brought  out  by 
the  approximate  curves  given  in  Fig.  7,  which 
give  the  horsepower  required,  and  horsepower 
available  at  various  speeds  for  a  fast  reconnais- 
sance type  of  aeroplane  of  refined  design.  The 
full  lines  give  the  power  available  for  a  fixed- 
blade  propeller;  the  dotted  lines  for  a  variable- 
angle  blade.  It  is  assumed  that  the  propeller 
was  designed  for  maximum  efficiency  at  the  high 
speed  of  the  aeroplane. 

The  most  evident  gain  made  by  using  the 
variable  pitch  as  observed  from  the  curves  is  the 


254 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


increased  reserve  horsepower  available  for 
climbing.  This  particular  assumed  aeroplane, 
with  full  load,  climbs: 

With  fixed  blade:     650  ft.  the  first  minute. 


Fig.  7 — Performance  curves  for  reconnaissance  type  of  aeroplane 

With  variable-pitch  blade:  715  ft.  the  first 
minute. 

The  increase  in  the  radius  of  action  is  very 
great,  the  greatest  radius  of  action  being  ob- 


u» 


««0 


/f 

/ 

/ 

J'^' 

/ 

/ 

/ 

V 

^ 

^ 

/ 

/ 

\,^ 

— --'  1 

■J 

^^- 

1 

0 

to  «a  70  so 

SPCCO.  MILCS  PCR  HOUR 


Fig.  9 — Showing  economical   speeds  of  aeroplanes  with  flxed- 
bUde  (full  lines)  and  variable-blade  (dotted  lines)  propellers 

tained  when  flying  at  the  economical  speed  of 
the  aeroplane.     Figure  8  shows  the  economical 
speed  in  each  case. 
On  one  filling  of  the  gasoline  tanks  the  fixed 


blade  would  carry  the  machine  about  690  miles 
in  10^  hours.  The  variable-pitch  blade  would 
carry  the  same  machine  a  distance  of  about  10.50 
miles  in  15i/^  hours.  (Were  this  machine 
driven  at  fuU  power  it  could  go  but  600  miles 
with  either  propeller. ) 

These  cures,  while  only  approximate,  will  at 
least  give  some  indication  as  to  the  value  of  a 
variable-angle  propeller,  especially  where  great 
distances  are  to  be  covered. 

The  greater  efficiency  of  the  variable  pitch 
would  be  of  value  in  giving  increased  climbing 


Angle  of  Attach 


ability  at  high  altitudes  and  the  possibility  of 
reaching  greater  heights  with  a  given  machine. 

Another  feature  possible,  of  secondary  impor- 
tance, in  a  variable-pitch  blade  is  that  it  can  be 
rotated  to  give  a  large  negative  angle  of  attack, 
or  possibly  reversed,  when  the  aeroplane  is  on 
the  ground  making  a  landing,  thus  serving  as  a 
brake  and  cutting  down  the  distance  the  ma- 
chine rolls  on  the  ground, 

APPENDIX 

The  weight  of  assumed  aeroplane  fully  loaded 
is  2400  lbs.  The  brake  horsepower  of  engine  is 
as  given  in  Fig.  11.  The  fuel  capacity  is  six 
hours  at  full  power. 

If  A  denotes  the  angle  that  the  helix  line 
makes  with  the  base  line.  Fig.  9,  V  the  transla- 
tional  velocity  in  feet  per  second  and  iV  the  pro- 
peller speed  in  revolutions  per  second,  then  the 
distance  advanced  each  revolution,  neglecting 
slip,  is  (r-^2V)  ft.,  which  is  the  effective  pitch 
of  the  propeller. 

Suppose  the  chord  XF  of  the  blade  section  at 
any  radius  V ,  makes  an  angle  a  with  the  lielix 
line.  Fig.  9.  Angle  a  is  called  the  angle  of  at- 
tack of  the  section.  As  {V-^N)  changes 
owing  to  a  variation  in  either  V  or  N,  or  in  both 
the  blade  section  will  liave  a  varying  angle  of 
attack,  an  increase  in  {V -^  N)  decreasing  the 
angle  of  attack  and  vice  versa. 


SOME  PROBLEMS  IN  AEROPLANE  CONSTRUCTION 


255 


The  efficiency  of  such  an  element  is  expressed 


by 


c  = 


tan^ 


tan  {A  +  G) 


where  G  is  the  gliding  angle,  which  is  a  func- 
tion of  the  angle  of  attack  and  varies  with  the 


--^ 

^ 

\" 

' 

>' 

^■■/ 

y 

\ 

i 

/ 

/ 

\ 

/ 
/ 

/ 

\ 

1 

f 
1 

1 

1 

t 

/ 
/ 

/ 

■cpeller 
Propeller 



__w   Van 

fble-f>ifth 

1 

!  / 

/ 

1    / 
1  / 
t  / 

t  / 

1/ 

2 
DISTANCE 

4 
ADVANCE 0  f 

>tR  REVOLU 

TiOH.FErr 

• 

Fig.  10 

type  of  section  employed.  With  the  usual  sec- 
tion used  in  propeller  design  G  is  a  minimum 
when  the  angle  of  attack  is  about  4  deg.     It 


750  1000  nV>  IKK) 

REVOLUTIONS  PER  MINUTE 


This  can  be  accomplished  by  means  of  a  flex- 
ible blade  whose  pitch  angles  could  be  changed 
a  varying  amount  from  the  tip  of  the  blade  to 
the  root  or  hub  section.  Such  a  blade  is  out  of 
the  question  in  the  light  of  present  day  practice. 
A  good  approximation  to  such  a  blade  could  be 
more  simply  had  by  rotating  the  blade  about  its 
axis  perpendicular  to  the  shaft.  With  the  usual 
type  of  section  employed  the  approximation  is 
good  as  the  value  of  G  does  not  change  greatly 
for  a  degree  or  so  on  either  side  of  the  best  angle 
of  attack.  A  mean  value  for  the  angle  of  at- 
tack could  therefore  be  found  giving  practically 
the  same  efficiency  as  though  all  the  sections 
were  at  the  best  angle  of  attack. 

Fig.  10  shows  curves  in  which  efficiency  of  a 
propeller  is  plotted  against  {V-^'N).  The 
full  line  gives  the  efficiency  for  a  fixed  blade,  the 
dotted  line  the  efficiency  of  the  same  blade  were 
the  angle  of  attack  kept  at  approximately  4  deg. 
It  is  assumed  that  the  fixed-blade  propeller  was 
designed  for  a  maximum  efficiency  at  a  value  of 
(r^2V),of  about  6  ft. 

Propeller  Stresses 

In  connection  with  the  subject  of  propellers, 
it  may  be  of  interest  to  give  a  brief  review  of 
the  variation  of  stress  that  occurs  in  a  propeller 
blade  under  an  assumed  condition  of  flight. 

The  blades  of  a  propeller  are  subject  to  the 
following  stresses  when  an  aeroplane  is  in  any 
but  a  straight-line  flight: 


Fig.  13 — Points  of  maximum  propeller  stress 


Fig.  11- 


-Assumed  brake  horsepower  of  Engine  Driving  variable- 
pitch   propeller 


1.  Shear  due  to  aerodynamical  forces. 

2.  Torsion  due  to  the  distance  between  the 
would  therefore  be  advantageous  from  the  view-  center  of  gravity  of  the  blade  section  and  the 
point  of  efficiency  of  the  section  to  keep  the  point  of  application  of  the  resultant  of  the  air 
angle  of  attack  at  4  deg.  throughout  the  speed    reactions. 

of  the  aeroplane.  3.  Tension  due  to  centrifugal  force. 


256 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


4.  Steady  bending  due  to  aerodynamic 
forces ;  torque  and  thrust  imposing  a  distributed 
load  on  the  blade,  the  hub  being  the  fixed  point 
of  support. 

5.  Reverse  bending  due  to  gjToscopic  forces, 
which  occurs  only  when  the  aeroplane  has  rota- 
tion about  an  axis,  as  in  making  a  turn  or  pull- 
ing out  of  a  dive.  As  a  matter  of  fact,  an  aero- 
plane is  continually  turning  to  some  extent  if 
the  flight  be  in  disturbed  air. 

Each  of  these  forces  produces  a  maximum 
stress  of  tension  and  compression  in  different 
parts  of  the  blade,  hence  the  resultant  fiber 
stress  at  any  point  will  be  equal  to  the  algebraic 
sum  of  the  individual  stresses  at  that  point. 

It  is  sufficient  to  calculate  the  stress  at  the 
points  a,  b,  c,  (Fig.  12)  along  the  blade,  as  these 
points  will  be  those  of  maximum  stress. 

The  shear  in  any  case  is  small  and  can  be  neg- 
lected in  design.  The  torsion  is  also  small.  In 
good  designs,  when  the  thrust  is  great,  the  point 
of  application  of  the  air  reactions  is  but  little 
removed  from  the  axis  passing  through  the  cen- 
ter of  gravity  of  the  section. 

The  curves  of  stress  given  are  for  a  three- 
blade  propeller  of  about  S^A  ft.  diameter,  5  ft. 
pitch,  absorbing  150  h.p.  at  1300  r.p.m.     The 


^ r 

JIABIUS  IN    rccT 


5h5» 
Pig.  IS— Fiber  stress  In  propeller  blade  at  point  o  (See  Fig.  12) 


curves  are  not  accurate,  as  they  are  intended 
merely  to  give  a  general  idea  of  the  order  of 
magnitude  of  the  stresses  likely  to  occur  in  such 
a  propeller. 

The  stress  caused  by  centrifugal  force  is  uni- 
form over  any  section  of  the  blade  and  varies  in 
intensity  at  points  along  the  blade,  as  shown  ap- 
proximately in  Figs.  18,  14  and  15. 


Steady  bending  due  to  aerodjmamic  forces  is 
caused  by  torque  and  thrust.  These  forces  act 
along  X — X  and  Y — Y,  respectively  for  any 
section,  such  as  shown  in  Fig.  12.  When  re- 
solved along  I — I  and  II — II  they  induce  bend- 
ing moments  that  cause  the  fiber  stress  as  shown 
in  Figs.  13,  14  and  15. 

Gyroscopic  moments  are  only  induced  when 
the  aeroplane  is  changing  its  direction  of  flight. 
In  order  to  estimate  the  stress  set  up  in  the 
blades  an  assumption  must  be  made  as  to  the 
angular  velocitj^  of  the  propeller  axis;  that  is, 
as  to  the  precession.  There  is  some  question 
as  to  the  assumption  it  is  reasonable  to  make  in 
computing  the  stresses.  The  type  of  aeroplane, 
size  and  disposition  of  the  larger  masses,  such 
as  engines,  etc.,  will  affect  the  rate  at  which  a 
machine  can  be  turned  in  flight.  In  general, 
the  angular  velocity  in  yaw  will  not  greatly 
exceed  0.35  radians  per  second.  It  must  be  re- 
membered, however,  that  a  steeply -banked  turn 
also  involves  rotation  in  pitch. 

The  maximum  angular  velocity  attained  in 
coming  out  of  a  steep  dive  can  be  estimated  from 
the  characteristics  of  the  aeroplane  and  the  fac- 
tor of  safety,  which  determine  the  maximum 


RAOWS    IN    FCCT 


Fig.  14 — Stress  in  propeller  blade  at  point  6  (See  Fig.  12) 

high  speed  attainable  and  the  radius  of  curva- 
ture of  the  path  along  which  it  is  possible  to  pull 
the  machine  out  of  its  dive  safely.  A  safe  value 
for  the  angular  velocity  in  pitch  for  the  usual 
type  of  present-day  aeroplanes  is  about  one  ra- 
dian per  second.  Loops  have  been  turned  in 
about  6  seconds,  which  gives  about  the  value 
mentioned  of  the  angular  velocity. 

A  precession  of  one  radian  per  second  at  the 


SOME  PROBLEMS  IN  AEROPLANE  CONSTRUCTION 


257 


normal  speed  of  the  engine  should  therefore  be 
assumed  in  computing  the  stresses. 

The  stresses  set  up  by  gyroscopic  forces  are 
alternating,  changing  in  sign  (tension  to  com- 
pression) twice  in  each  revolution  of  the  propel- 
ler about  its  axis. 


RADIUS  m  FEET 

Fig.  15 — Stress  in  propeller  blade  at  point  c  (See  Fig.  12) 

The  fiber  stress  caused  by  the  gyroscopic  mo- 
ments is  given  in  Figs.  13,  14  and  15.  Alge- 
braically adding  the  fiber  stress  at  the  three 
points  chosen  gives  the  approximate  value  of  the 
resultant  fiber  stress  at  those  points,  as  shown 
in  the  same  figures. 

It  will  be  noticed  that  the  maximum  stresses 
occur  at  some  distance  out  from  the  hub.  To 
insure  a  good  wearing  blade,  which  will  stand 
up  under  the  necessarily  hard  usage  given  it 
in  the  field,  a  factor  of  safety  of  not  less  than 
5  is  suggested  as  being  the  minimum  consistent 
with  requirements  when  the  three  principal 
stresses  are  taken  into  consideration. 

Suggestions  for  Improvements  in  Design 

These  suggestions  on  powerplants  are  based 
on  the  experience  of  the  First  Aero  Squadron, 
United  States  Army,  in  the  field. 

It  is  considered  extremely  poor  practice  to  use 
shims  under  caps  of  crankpin  and  crankshaft 
bearings. 

JNIany  American  crankcases  are  not  suf- 
ficiently rigid  in  construction.  It  is  believed 
that  crankcase  castings  are  not  designed  and 
built,  in  this  country,  with  sufficient  care.  Some 
of  the  jigs  for  boring  crankshaft  and  camshaft 
bearing  seats  are  not  so  accurate  as  desirable. 


In  some  cases  it  has  been  found  that  pistons 
are  not  of  uniform  weight,  and  are  not  carefully 
made. 

Lack  of  inter  changeability  of  parts  and  care- 
less workmanship  have  been  great  faults  in  this 
country. 

OILING   SYSTEM 

This  should  be  by  pressure  to  all  important 
bearings,  preferably  from  a  gear  pump. 
Screens  should  be  provided  to  protect  the  suc- 
tion pumps.  For  engines  that  have  push-rod 
and  rocker-arm  valve  mechanism,  means  should 
be  provided  to  reduce  the  friction  on  the  ex- 
haust-valve rocker-arm  bearing,  especially  if 
the  valves  are  more  than  1^/4  in.  diameter, 

IGNITION 

All  military  aeroplanes,  except  possibly  the 
pursuit  type,  should  have  two  complete  and  in- 
dependent ignition  systems. 

Engines  larger  than  140  h.p.  should  have  a 
booster  system  for  starting  on  battery  spark,  if 
a  starter  is  not  provided. 

It  is  believed  that  our  magnetos  would  have 
much  longer  life  if  a  more  suitable  shock-ab- 
sorbing device  between  the  driving  gear  and 
the  magneto  shaft  were  provided,  A  magneto 
mounting  should  be  machined  so  that  the  mag- 
neto shaft  will  be  exactly  in  line  with  its  driving 
shaft;  dowel  pins  and  dowel-pin  holes  to  pre- 
serve this  alignment  should  be  provided.  No 
shims  should  be  used  here.  We  have  had  con- 
siderable trouble  because  of  non-uniform  and 
warped  carbon  brushes. 

FUEL   SUPPLY 

Carbureters  should  be  located  in  such  a  way 
that  oil,  water  and  impurities  cannot  enter  them. 
They  should  be  supported  from  the  engine  and 
not  from  the  frame  work  of  the  aeroplane. 
They  should  be  supported  independently  of  the 
intake  manifolds,  if  practicable. 

Gaskets  for  connections  in  intake  manifolds 
should  be  as  thin  as  practicable.  Manifolds 
built  of  copper,  brazed,  or  of  steel,  welded,  are 
considered  preferable  to  cast  manifolds.  Steel 
is  considered  preferable,  but  should,  of  course, 
be  heat  treated  after  welding. 


258 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


It  is  urged  that  more  study  and  care  should 
be  put  into  the  design  relating  to  shape  and  fin- 
ish of  the  interior  of  intake  manifolds  and  pas- 
sages. It  is  believed,  in  this  connection,  that 
much  greater  efficiency  can  be  obtained  by  at- 
tention to  fluid  flow. 

COOLING   SYSTEM 

Radiators  should  preferably  be  placed  at  the 
leading  edge  of  the  upper  wing,  the  header  be- 
ing shaped  so  as  to  form  part  of  this  leading 
edge.     If  it  is  necessary  to  place  the  radiator 


between  the  engine  and  the  propeller,  the  radia- 
tor should  be  circular.  The  radiator  should  be 
provided  with  a  sufficient  number  of  points  of 
support  to  prevent  deformation  of  the  shell  ow- 
ing to  shocks  on  landing. 

Care  should  be  taken  with  the  alignment  of 
tubes  at  the  connections  in  the  water-circulating 
system.  A  ring  reinforcement  might  be  welded 
to  a  flanged  end  of  the  thin  tubing  and  the  face 
machined  so  as  to  make  a  good  fit  to  the  cylin- 
der jacket.  It  is  considered  bad  practice  to  ex- 
pand thin  tubing. 


Memoranda: 


CHAPTER  XX 


METHODS  OF  MEASURING  AIRCRAFT  PERFORMANCES 

By  Capt.  H.  T.  TizAKi),  R.F.C. 


Aeroplane  Testing 

The  accurate  testing  of  aeroplanes  is  one  of 
the  many  branches  of  aeronautics  which  have 
been  greatly  developed  during  the  war,  and  es- 
pecially during  the  last  year.  For  some 
months  after  the  war  began  a  climb  of  3,000  to 
5,000  ft.  by  aneroid  and  a  run  over  a  speed 
course  was  considered  (juite  a  sufficient  test  of  a 
new  aeroplane;  now  we  all  realize  that  for  mili- 
tary reasons  certainly,  and  probably  for  com- 
mercial reasons  in  the  future,  it  is  the  perform- 
ance of  a  machine  at  far  greater  heights  with 
which  we  are  mainly  concerned.  In  this  paper 
I  propose  to  give  a  short  general  account  of 
some  of  the  methods  of  testing  now  in  use  at  the 
Testing  Squadron  of  the  Royal  Flying  Corps, 
and  to  indicate  the  way  in  which  results  of  actual 
tests  may  be  reduced,  so  as  to  represent  as  ac- 
curately as  possible  the  performance  of  a  ma- 
chine independently  of  abnormal  weather  con- 
ditions, and  of  the  time  of  the  year.  For  ob- 
vious reasons  full  details  of  the  tests  and  meth- 
ods employed  cannot  yet  be  given.  So  far  as 
England  is  concerned,  I  believe  that  the  general 
principles  of  what  may  be  called  the  scientific 
testing  of  aeroplanes  were  first  laid  down  at  the 
Royal  Aircraft  Factory,  Our  methods  of  re- 
duction were  based  on  theirs  to  a  considerable 
extent,  with  modifications  that  were  agreed 
upon  between  us;  thejj^  have  been  still  further 
modified  since,  and  recently  a  joint  discussion 
of  the  points  at  issue  has  led  to  the  naval  and 
military  tests  being  coordinated,  so  that  all  of- 
ficial tests  are  now  reduced  to  the  same  stand- 
ard. It  should  be  emphasized  that  once  the 
methods  are  thought  out  scientific  testing  does 
not  really  demand  anv  high  degree  of  scientific 
knowledge ;  in  the  end  the  acciu-acy  of  the  results 
really  depends  upon  the  flyer,  who  must  be  pre- 


pared to  exercise  a  care  and  patience  unneces- 
sary in  ordinary  flying.  Get  careful  flyers 
whose  judgment  and  reliabilitj'^  you  can  trust 
and  your  task  is  comparatively  easy;  get  care- 
less flyers  and  it  is  impossible. 

At  the  outset  it  may  be  useful  to  point  out  by 
an  example  the  nature  of  the  problems  that  drise 
in  aeroplane  testing.  Suppose  that  it  is  desired 
to  find  out  which  of  two  wing  sections  is  most 
suitable  for  a  given  aeroplane.  The  aeroplane 
is  tested  with  one  set  of  wings,  which  are  then 
replaced  by  the  other  set  and  the  tests  repeated 
some  days  later.  The  results  might  be  ex- 
pressed thus: 

A  Wings. 


Speed    at    10,000 

ft 

Rate  of  climb  at 

10,000  ft 250  ft 


90  m.p.h.. 


B  Wings. 
93  m.p.h. 


a  minute.    300  ft.  a  minute. 


259 


Now,  the  intelligent  designer  knows,  or  soon 
will  know,  that,  firstly,  an  aneroid  may  indicate 
extremely  misleading  "heights":  and,  secondly, 
that  even  if  the  actual  height  above  the  ground 
is  the  same  in  the  two  tests,  the  actual  conditions 
of  atmospheric  pressure  and  temperature  may 
have  been  very  different  on  the  two  days.  He 
will  therefore  say.  What  does  that  10,000  mean? 
Do  you  mean  that  yoiu*  aneroid  read  10,000  ft., 
or  do  you  mean  10,000  ft.  above  the  spot  you 
started  from,  or  10,000  ft.  above  sea-level?  If 
he  proceeds  to  think  a  trifle  further  he  will  say, 
What  was  the  density  of  the  atmosphere  at  your 
10,000  ft.;  was  it  the  same  in  the  two  tests?  If 
not,  the  results  do  not  convey  much.  There  he 
will  touch  the  keynote  of  the  whole  problem,  for 
it  is  on  the  density  of  the  atmosphere  that  the 
whole  performance  of  an  aeroplane  depends; 
the  power  of  the  engine  and  the  efficiency  of  the 
machine  depends  essentially  on  the  density,  the 
resistance  to  the  motion  of  the  machine  through 


260 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


the  air  is  proportional  to  the  density,  and  so 
finally  is  the  lift  on  the  wings.  None  of  these 
properties  are  proportional  solely  to  the  pres- 
sure of  the  atmosphere,  but  to  the  density — that 
is,  the  weight  of  air  actually  present  in  unit  vol- 
ume. It  follows  that  it  is  essential  when  com- 
paring the  performances  of  machines  to  com- 
pare them  as  far  as  possible  under  the  same 
conditions  of  atmospheric  dcnmti/,  not  as  is 
loosely  done  at  the  same  height  above  the  earth, 
since  the  density  of  the  atmos])here  at  the  same 
height  above  the  earth  may  vary  considerably  on 
different  days,  and  on  the  same  day  at  different 
places. 


-zoooo 


I6O0O 


ISOOO 


fiooo 


VartJtl 

Fig.  I. 

ions  of  lemaerature  uiilh  Heiifht. 

-' 

\\ 

\ 

\& 

\  \''* 

V-. 

\  1 

v^,_ 

Jo  So  la 

TEMPERATURE 


90 


At  the  same  time,  in  expressing  the  final  re- 
.sults,  this  principle  may  be  carried  too  far. 
Thus,  if  the  speed  of  a  machine  were  exjiressed 
as  40  meters  a  second  at  a  density  of  0.8  kilogs. 
per  cubic  meter,  the  statement,  though  it  may  be 
strictly  and  scientifically  accm-ate,  will  convey 
nothing  to  99  per  cent,  of  those  directly  con- 
cerned with  the  results  of  the  test.  The  result 
is  rendered  intelligible  and,  indeed,  useful  by 
the  form,  "90  m.p.h.  at  10,000  ft.,"  or  whatever 
it  is.  With  this  form  of  statement,  in  order 
that  all  the  statements  of  results  may  be  con- 
sistent and  comparative,  we  must  be  careful  to 
mean  by  "10,000  ft."  a  certain  definite  density 
— in  fact,  the  average  density  of  the  atmosphere 
at  a  height  of  10,000  ft.  above  mean  sea-level. 
This  is  what  the  problem  of  "reduction"  of  tests 
Imils  down  to:  what  is  the  relation  between  at- 
mospheric density  and  height  above  sea-level? 


This  knowledge  is  obtained  from  meteorological 
observations.  We  have  collected  all  the  avail- 
able data,  mostly  unpublished,  with  results 
shown  in  the  following  table: — 

Table  1. — Mean  Atmospheric  Pressure,  Temperature 
and  Density  at  various  Heights  above  Sea-level. 


Mean  temp. 

Mean 

Height 

Height   in 

Mean 

in  absolute 

density  in 

in 

equivalent 

pressure  m 

degrees 

kgm.  per 

Kiloms. 

feet. 

millibars. 

Centigrade. 

cubie  meter 

0 

0 

1,014 

282 

1.253 

1 

3,280 

900 

278 

1.128 

2 

6,560 

795 

273 

1.014 

3 

9,840 

699 

268 

0.909 

4 

13,120 

615 

262 

0.818 

5 

16,400 

568 

255 

0.735 

6 

19,680 

469 

248 

0.658 

7 

22,960 

407 

241 

0.589 

These  are  the  mean  results  of  a  long  series  of 
actual  observations  made  mainly  by  Dr.  J.  S. 
Dines.  It  is  convenient  to  choose  some  density 
as  standard,  call  it  unity,  and  refer  to  all  other 
densities  as  fractions  or  percentages  of  this 
"standard  density."  We  have  taken,  in  con- 
formity with  the  R.A.F.,  the  density  of  dry 
air  at  760  mm.  pressure  and  16°  C.  as  our  stand- 
ard density;  it  is  1.221  kilog.  per  cubic  meter. 
The  reason  this  standard  has  been  taken  is  that 
the  air  speed  indicators  in  use  are  so  constructed 
as  to  read  correctly  at  this  density,  assuring  the 
law :  p  =  VipY^,  where  V  is  the  air  s])eed.  p  the 
pressure  oI)tained,  i>  the  standard  density. 

In  some  ways  it  would  doubtless  be  more  con- 
venient to  take  the  average  density  at  sea-level 
as  the  standard  density,  but  it  does  not  really 
matter  what  you  take  so  long  as  you  make  your 
units  quite  clear.  Translated  into  feet,  and 
fraction  of  the  standard  density,  the  above  table 
becomes : — 


Table  II. 

Height 
in  feet. 

Percentage 

of  standarc 

density. 

Height 
in  feet. 

Percentage 
of  standard     Height 
density.        in  feel. 

Percentage 

of  standard 

density. 

0 

102.6 

7.000 

81.9 

15,000 

63.0 

1,000 

99.4 

8,000 

79.2 

16.000 

61.1 

2.000 

96.3 

9,000 

76.5 

1 16.500 

60.1 

3,000 

93.2 

tl  0,000 

74.0 

17.000 

.59.1 

4.000 

90.3 

11.000 

71.7 

18.000 

.57.1 

5.000 

87.4 

12,000 

69.5 

19.000 

.55.2 

6,000 

84.6 

1 13,000 

67.3 

20.000 

53.3 

t6,500 

83.3 

14,000 

65.2 

METHODS  OF  MEASURIXG  AIRCRAFT  PERFORMANCES 


261 


Let  us  briefly  consider  what  these  figures 
mean.  For  example,  we  say  that  the  density 
at  10,000  ft.  is  74  per  cent,  of  our  standard 
density,  but  it  is  not  meant  that  at  10,000 
ft.  above  mean  sea  level  the  atmospheric 
density  will  always  be  74  per  cent,  of  the  stand- 
ard density.  Unfortunately  for  aeroplane 
tests  this  is  far  from  true.  The  atmospheric 
density  at  any  particular  height  may  vary  con- 
siderably from  season  to  season,  from  day  to 
day,  and  even  from  hour  to  hour;  what  we  do 
mean  is  that  if  the  density  at  10,000  ft.  could  be 
measured  everj^  day,  then  the  average  of  the  re- 
sults would  be,  as  closely  as  we  can  tell  at  pres- 
ent, 74  per  cent,  of  the  standard  density. 

The  above  table  may  therefore  be  taken  to 
represent  the  conditions  prevailing  in  a  "nor- 
mal" or  "standard"  atmosphere,  and  we  en- 
deavor, in  order  to  obtain  a  strict  basis  of 
comparison,  to  reduce  all  observed  aeroplane 
performances  to  this  standard  atmosphere,  i.e., 
to  express  the  final  results  as  the  performance 
which  may  be  expected  of  the  aeroplane  on  a 
day  on  which  the  atmospheric  density  at  every 
point  is  equal  to  the  average  density  at  the  point. 
Some  days  the  aeroplane  may  put  up  a  better 
performance,  some  days  a  worse,  but  on  the 
average,  if  the  engine  power  and  other  charac- 
teristics of  the  aeroplane  remain  the  same,  its 
performance  will  be  that  given. 

It  must  be  remembered  that  a  standard  at- 
mosphere is  a  very  abnormal  occurrence;  be- 
sides changes  in  density  there  may  occur  up- 
and-down  air  currents  which  exaggerate  or 
diminish  the  performance  of  an  aeroplane,  and 
which  must  be  taken  carefully  into  account. 
They  show  themselves  in  an  otherMise  imac- 
countable  increase  or  decrease  in  rate  of  climb 
or  in  full  speed  flj'ing  level  at  a  particular 
lieight. 

We  now  pass  to  the  actual  tests,  beginning 
with  a  description  of  the  observations  which 
have  to  be  made  and  thereafter  to  the  instru- 
ments necessary.  The  tests  resolve  themselves 
mainly  into  (a)  A  climbing  test  at  the  maxi- 
mum rate  of  climb  for  the  machine,  {h)  Speed 
tests  at  various  heights  from  the  "ground"  or 
some  other  agreed  low  level  upwards. 

Experience  agrees  with  theory  in  showing 


that  the  best  climb  is  obtained  by  keeping  that 
which  is  frecjuently  called  the  air  speed  of  an 
aeroplane,  viz.,  the  indications  of  the  ordinary 
air  speed  indicator,  nearly  constant  whatever 
the  height — in  other  words,  pV  is  kept  con- 
stant. We  can  look  at  this  in  this  way.  There 
is  a  limiting  height  for  every  aeroplane  above 
which  it  cannot  climb;  at  this  limiting  height, 
called  the  ceiling  of  the  machine,  there  is  only 
one  speed  at  which  the  aeroplane  will  fly  level, 
at  any  other  air  speed  higher  or  lower  it  will 
descend.  Suppose  this  speed  be  55  m.p.h.  on 
the  air  speed  indicator.  Then  the  best  rate  of 
climb  from  the  ground  is  obtained  by  keeping 
the  speed  of  the  machine  to  a  steady  indicated 
55  m.p.h.  Fortunately  a  variation  in  the  speed 
does  not  make  very  much  diff'erence  to  the  rate 
of  climb;  for  instance,  a  B.E.2c  with  a  maxi- 
mum rate  of  climb  at  53  m.p.h.  climbs  just  as 
fast  up,  say,  5,000  ft.  at  about  58  m.p.h.  This 
is  fortunate  as  it  requires  considerable  concen- 
tration to  keep  climbing  at  a  steady  air  speed, 
especially  with  a  light  scout  machine;  if  the  air 
is  at  all  "bumpy"  it  is  impossible.  At  great 
heights  the  air  is  usually  very  steady,  and  it  is 
much  easier  to  keep  to  one  air  speed.  It  is 
often  difficult  to  judge  the  best  climbing  speed 
of  a  new  machine;  flyers  differ  very  much  on 
this  point,  as  on  most.  The  Testing  Squadron, 
therefore,  introduced  some  time  ago  a  rate  of 
climb  indicator  intended  to  show  the  pilot  when 
he  is  climbing  at  the  maximum  rate.  It  con- 
sists of  a  thermos  flask,  communicating  with  the 
outer  air  through  a  thermometer  tube  leak.  A 
liquid  pressure  gage  of  small  bore  indicates  the 
difference  of  pressure  between  the  inside  and 
outside  of  the  vessel.  Now,  when  climbing,  the 
atmospheric  pressure  is  diminishing  steadily; 
the  pressvu'e  inside  the  thermos  flask  tends 
therefore  to  become  greater  than  the  outside 
atmospheric  pressure.  It  goes  on  increasing 
until  air  is  being  forced  out  through  the  ther- 
mometer tubing  at  such  a  rate  that  the  rate  of 
change  of  pressure  inside  the  flask  is  equal  to 
the  rate  of  change  of  atmospheric  pressure  due 
to  climbing.  When  chmbing  at  a  maximum 
rate,  therefore,  the  pressure  inside  the  thermos 
flask  is  a  maximum.  The  pilot  therefore  varies 
his  air  speed  until  the  liquid  in  the  gage  is  as 


262 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


high  as  possible,  and  this  is  the  best  climbing 
speed  I'or  the  machine. 

What  observations  during  the  test  are  neces- 
sary in  order  that  the  results  may  be  reduced 
to  the  standard  atmosphere?  Firstly,  we  want 
the  time  from  the  start  read  at  intervals,  and  the 
height  reached  noted  at  the  same  time.  Here 
we  encounter  a  difficulty  at  once,  for  there  is  no 
instrument  which  records  height  with  accuracy. 
The  aneroid  is  an  old  friend  now  of  aeronauts 
as  well  as  of  mountaineers,  but  although  it  has 

riCuKE      2 


X^OAr 


^•-■86;  g     S^*.oseOPf 


often  been  tentatively  exposed,  it  is  doubtful 
whether  1  i)er  cent,  of  those  who  use  it  daily 
realize  how  extraordinarily  rare  it  is  that  it  ever 
does  what  it  is  supposed  to  do,  that  is,  indicate 
the  correct  height  above  the  ground,  or  starting 
jjlace.  The  faults  of  the  aeroplane  aneroid  are 
partly  unavoidable  and  partly  due  to  those  who 
first  laid  down  the  conditions  of  its  manufac- 
ture. An  aneroid  is  an  instrument  which  in  the 
first  place  measures  only  the  pressure  of  the 
surrounding  air.  Now  if  pi  and  po  are  the 
pressure  at  two  points  in  the  atmosphere,  the 
difference  of  height  between  these  points  is 
given  very  closely  by  the  relation,  h  —  <^  log, 
'"/p2  where  ^  is  the  average  temperature,  ex- 
pressed in  "absolute"  degrees,  of  the  air  between 
the  two  ])oints.  It  is  obvious  that  if  we  wish 
to  graduate  an  aneroid  in  feet  we  must  choose 
arbitrarily  sonie  value  for  *.  The  temperature 
that  was  originally  chosen  for  aero|)lnne  ane- 
roids was  .50''  F.  or  10''  C.  An  aneroid,  as  now 
graduated,  will  therefore  only  read  the  correct 
height  in  feet  if  the  atmosphere  has  a  uniform 
temperature  of  .50°   F.  from  the  ground  up- 


wards, and  it  will  be  the  more  inaccurate  the 
greater  the  average  temperature  between  the 
ground  and  the  height  reached  differs  from  .50^ 
F.  Unfortunately  50°  F.  is  nuich  too  high  an 
average  temperature ;  to  take  an  extreme  exam- 
ple, it  is  only  on  the  hottest  days  in  summer,  and 
even  then  very  rarely,  that  the  average  tempera- 
ture between  the  ground  and  20,000  ft.  will  be 
as  high  as  50°  F.  On  these  very  rare  occasions 
an  aneroid  will  read  approximately  correctly  at 
high  altitudes;  otherwise  it  will  always  read  too 
high.  In  winter  it  may  read  on  cold  days  2,000 
ft.  too  high  at  16,000  ft.,  i.e.,  it  will  indicate  a 
height  of  16,000  ft.  when  the  real  height  is  only 
14,000  ft.  It  is  always  necessary,  therefore,  to 
"correct"  the  aneroid  readings  for  temperature. 
The  equation 

Tx  _  273  +  t    , 

gives  us  the  necessary  correction.  Here  H  is 
the  true  difference  in  height  between  any  two 
points,  t  the  average  temperature  in  degrees 
Centigrade  between  the  points,  and  h  the  differ- 
ence in  height  indicated  by  aneroid.  It  is  con- 
venient to  draw  a  curve  showing  the  necessary 
correction  factors  at  different  temperatures, 
some  of  which  are  given  below: — 

Tabi.e  III. — .Aneroid  Correction  Factors. 

Temperature  Correction  Temperature  Correction 

°  F.                       factor.  "  F.  factor. 

70                  1.04.0  10  0.9522 

50                  1.000  —10  0.833 
30                  0.961 

For  example  if  a  climb  is  made  through  1,000 
ft.  by  aneroid  and  the  average  temperature  is 
10°  v.,  the  actual  distance  in  feet  is  only 
1,000  X  0.922  =  922  ft.  The  above  equation 
is  probably  quite  accurate  enough  for  small  dif- 
ferences of  height — up  to  1,000  ft.  say — and  ap- 
j)roximately  so  for  bigger  differences.  The 
magnitude  of  the  correction  which  may  be  nec- 
essary shows  how  important  it  is  that  observa- 
tions of  temperature  should  be  made  during 
every  test.  P"'or  this  purpose  a  special  tlier- 
mometer  is  attached  to  a  strut  of  the  machine, 
well  away  from  the  fuselage,  and  so  clear  of  any 
warm  air  which  may  come  from  the  engine. 


METHODS  OF  MEASURING   AIRCRAFT  PERFORMANCES 


263 


The  p^'rench,  I  believe,  do  not  measure  tempera- 
ture, but  note  the  ground  temperature  at  the 
start  of  a  test,  and  assume  a  uniform  fall  of 
temperature  with  height.  This,  undoubtedly, 
may  lead  to  serious  errors.  The  change  of  tem- 
perature with  height  is  usually  very  irregular, 
and  only  becomes  fairlj^  regular  at  heights  well 
above  10,000  ft. 

The  aneroid  being  what  it  is,  one  soon  comes 
to  the  conclusion  that  the  only  way  to  make  use 
of  it  in  aeroplane  tests  is  to  treat  it  purely  as  a 
pressure  instrument.  For  this  reason  it  is  best 
to  do  away  with  the  zero  adjustment  for  all 
test  purposes  and  lock  the  instrument  so  that 
the  zero  point  on  the  height  scale  corresponds 
to  the  standard  atmospheric  pressure  of  29.9  ins. 
or  760  mm.  of  mercury.  Every  other  height 
then  corresponds  to  a  definite  pressure;  for  in- 
stance, the  locked  aneroid  reads  5,000  ft.  when 
the  atmospheric  pressure  is  24.88  ins.,  and 
10,000  ft.  when  it  is  20.70  ins.,  and  so  on,  If 
the  temperature  is  noted  at  the  same  time  as  the 
aneroid  reading,  we  then  know  both  the  atmos- 
pheric pressure  and  temperature  at  the  point, 
and  hence  the  density  can  be  calculated,  or, 
more  conveniently,  read  off  curves  drawn  for 
the  purpose.  The  observations  necessary 
(after  noting  the  gross  aeroplane  weight  and 
net  or  useful  weight  carried)  are  therefore:  (i) 
Aneroid  height  every  1,000  ft.;  (ii)  time  which 
has  elapsed  from  the  start  of  the  climb;  and  (iii) 
temperature.  To  these  should  be  added  also 
(iv)  the  air  speed  and  (v)  engine  revolutions  at 
frequent  intervals.  The  observed  times  are 
then  plotted  on  squared  pa])er  against  the  ane- 
roid heights  and  a  curve  drawn  through  them. 
From  this  curve  the  rate  of  climb  at  any  part 
(also  in  aneroid  feet)  can  be  obtained  by  meas- 
uring tlie  tangent  to  the  curve  at  the  point. 
This  is  done  for  every  1,000  ft.  by  aneroid. 
The  true  rate  of  climb  is  then  obtained  by  mul- 
tiplying the  aneroid  rate  by  the  correction  fac- 
tor corresponding  to  the  observed  temperature. 
These  true  rates  are  then  plotted  afresh  against 
standard  heights,  and  from  this  curve  we  can 
obtain  the  rate  of  climl)  corresponding  to  the 
standard  heights,  1,000.  2,000,  3,000,  etc. 
Knowing  the  change  of  rate  of  climb  with 
height,  the  time  to  any  required  height  is  best 


obtained  by  graphical  integration.  The  table 
below  gives  the  results  of  an  actual  test. 

At  least  two  climbing  tests  of  every  new  ma- 
chine are  carried  out  up  to  16,000  ft.  or  over  by 
aneroid.  If  time  permits  three  or  more  tests 
are  made.  The  final  results  given  are  the  aver- 
age of  the  tests  and  represent  as  closely  as  pos- 
sible the  performance  on  a  standard  day,  with 
temperature  effects,  up  and  down  currents  and 
other  errors  eliminated. 

If  we  i^roduce  the  rate  of  climb  curve  up- 
wards it  cuts  the  height  axis  at  a  point  at  which 
the  rate  of  climb  would  be  zero,  and  therefore 
the  limit  of  climb  reached.  This  is  the  "ceiling" 
of  the  machine. 

SPEEDS 

His  16,000  ft.,  or  whatever  it  is,  reached,  the 
flyer's  next  duty  is  to  measure  the  speed  flying 
level  by  air  speed  indicator  at  regular  intervals 
of  heiglit  (generally  every  2,000  ft.)  from  the 
highest  point  downwards.  To  do  this,  he  re- 
quires a  sensitive  instrument  which  will  tell  him 
when  he  is  flying  level.  The  aneroid  is  quite 
useless  for  this  purpose,  and  a  "statoscope"  is 
used.  The  principle  of  this  instrument  is  really 
the  same  as  that  of  a  climb  meter.  It  consists 
of  a  thermos  flask  connected  to  a  small  glass 
gage,  slightly  cun^ed,  but  placed  about  hori- 
zontally (see  Fig.  2).  In  this  gage  is  a  small 
drop  of  liquid,  and  at  either  end  are  two  glass 
traps  which  prevent  the  liquid  from  escaping 
either  into  the  outside  air  or  into  the  thermos 
flask.  As  the  machine  ascends  and  the  atmos- 
pheric pressure  being  smaller,  and  the  pressure 
in  the  flask  being  higher  than  the  external  pres- 
sure, the  liquid  is  pushed  up  to  the  right  hand 
trap,  where  it  breaks,  allowing  the  air  to  escape. 
On  descending  the  reverse  happens;  the  liquid 
travels  to  the  left,  breaks,  and  air  enters  the 
flask.  When  flying  truly  level  the  drop  re- 
mains stationary,  moving  neither  up  nor  down. 
The  instrument  is  made  bv  the  British  Wright 
Co. 

The  flyer  or  the  observer  notes  the  maximum 
speed  by  the  air  speed  indicator — i.e.,  the  speed 
at  full  engine  throttle.  At  one  or  more  heights, 
also,  he  observes  the  speeds  at  various  positions 
of  the  throttle  down  to  the  minimum  speed 


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TEXTBOOK  OF  MILITARY  AERONAUTICS 


wliich  will  keep  the  machine  flying  at  the  height 
in  question.  The  petrol  consumption  and  the 
engine  revolutions  are  noted  at  the  same  time, 
as  well,  of  course,  as  the  aneroid  height  and 
temperature.  Accurate  observation  of  speeds 
needs  very  careful  flying — in  fact  much  more  so 
than  in  climbing  tests.  If  the  air  is  at  all 
bumpy  observations  are  necessarily  subject  to 
much  greater  error,  since  the  machine  is  always 
accelerating  and  decelerating.  The  best  way  to 
carry  out  the  test  seems  to  be  as  follows.  The 
machine  is  flown  first  just  down  hill  and  then 
just  up  hill,  and  the  air  speeds  noted.     This 


K 


Ficunc    3 


will  ^'e  a  small  range  between  which  the  real 
level  speed  must  lie.  The  flyer  must  then  keep 
the  speed  as  steadily  as  possible  on  a  reading 
midway  between  these  limits,  and  watch  the 
statoscope  with  his  other  eye.  If  it  shows 
steady  movement,  one  way  or  the  other,  the  air 
speed  must  be  altered  accordingly  by  1  m.p.h. 
In  this  way  it  is  always  possible  at  heights  where 
the  air  is  steady  to  obtain  the  reading  correct  at 
any  rate  to  1  m.p.h.,  even  with  light  machines, 
provided  always  sufficient  ])atience  is  exercised. 
The  r.p.m.  at  this  speed  are  then  noted. 

One  difficulty,  however,  cannot  be  avoided. 
If  at  any  height  there  is  a  steady  up  or  down 
air  current,  then  though  the  air  may  appear 
calm,  i.e.,  there  may  be  no  "bumps,"  the  air 
speed  indicator  reading  may  be  wrong,  since  to 
keep  the  machine  IcxtI  in  an  up  current  it  is 
necessary  to  fly  slightly  down  hill  relatively  to 
the  air.  Such  unavoidable  errors  are.  however, 
eliminated  to  a  large  extent  by  the  metliod  of 
taking  speeds  every  2,000  ft.,  and  finally  aver- 
aging the  results. 

We  must  now  consider  how  the  true  speed  of 
the  aeroplane  is  deduced  from  the  reading  of 
the  air  speed  indicator.     It  is  well  known  that 


an  air  speed  indicator  reads  too  low  at  great 
heights — for  example,  if  it  reads  70  m.p.h.  at 
8,000  ft.  the  real  speed  of  the  machine  through 
the  air  is  nearer  80  m.p.h.  The  reason  for  this 
is  that  the  indicator,  like  the  aneroid,  is  only  a 
pressure  gage — a  sensitive  pressure  gage,  in 
fact,  which  registers  the  difl'erence  of  pressure 
between  the  air  in  a  tube  with  its  open  end  point- 
ing forward  along  the  lines  of  flight  of  tlie  ma- 
cliine,  and  the  real  pressure  (the  static  ])ressure) 
of  the  external  air.  This  difference  of  pressure 
is  as  nearly  as  we  can  judge  by  experiment  — 
Vi  p  V^  (where  p  is  the  density  of  the  air  and  V 
the  speed  of  the  machine) ,  provided  that  the 
open  end  of  the  tube  is  well  clear  of  Avings, 
fuselage,  etc.,  and  so  is  not  affected  by  eddies 
and  other  disturbances.  Now,  assuming  this 
law,  air  speed  indicators  are  graduated  to  read 
correctly,  as  I  have  said  above,  at  a  density  of 
1.221  kgm.  per  cubic  meter,  which  we  have 
taken  as  our  standard  density  and  called 
"unity."  It  corresponds  on  an  average  to  a 
height  of  about  800  feet  above  sea  level. 

Then  suppose  the  real  air  sj^eed  of  an  aero- 
plane at  a  height  of  "h"  feet  is  V  m.p.h.,  and  the 
indicated  air  speed  is  70  m.p.h.,  this  means  that 
the  excess  pressure  in  the  tube  due  to  the  speed 
is  proportional  to  1  X  70^, 

or  P  X  F'^  =  1  X  70^ 

where  p  is  the  density  at  the  height  in  question, 
expressed  as  a  fraction  of  the  standard  density. 
To  correct  the  observed  speed,  we  therefore 
divide  the  reading  by  the  square  root  of  the 
density.  Thus,  observation  of  the  maximum 
speed  of  an  aeroplane  at  a  height  of  8,000  ft.  by 
the  locked  aneroid  gave  80  m.p.h.  on  the  indi- 
cator, the  temperature  })eing  31°  Fahr.  From 
the  cun'e  we  find  that  the  density  corresponding 
to  8.000  ft.  and  31"  is  0.8.'>  of  standard  density. 
The  corrected  air  speed  is  therefore: 


80 


V  .8.) 


86.7  m.p.h. 


This  "corrected"  air  speed  will  only  be  true 
if  the  above  law  holds,  that  is  to  say,  if  there 
are  no  disturbances  due  to  the  jjressure  head 
being  in  close  proximity  to  struts  or  wings.  It 
is  always  necessary  to  find  out  the  magnitude 


METHODS  OF  MEASURING  AIRCRAFT  PERFORMANCES 


265 


of  this  possible  error,  that  is,  to  calculate  the 
air  speed  meter,  and  the  only  waj'  to  do  this  is 
to  measure  a  real  air  speed  at  some  reasonable 
altitude  for  easy  observation  of  the  aeroplane 
by  actual  timed  observations  from  the  ground, 
and  from  these  timed  results  check  those  de- 
duced from  the  air  speed  indicator  readings. 
This  calibration  is  the  most  important  and  diffi- 
cult test  of  all,  since  on  the  accuracy  of  the  re- 
sults depends  the  accuracy  of  all  the  other  speed 
measurements.  It  can  either  be  done  by  speed 
trials  over  a  speed  course  close  to  the  ground, 
or  when  the  aeroplane  is  flying  at  a  considerable 
height  above  the  ground.  In  the  Testing 
Squadron  we  have  always  attached  much  more 
importance  to  the  latter  method,  mainly  be- 
cause the  conditions  approximate  more  to  the 
conditions  of  the  ordinary  air  speed  measure- 
ments at  different  heights,  and  because  the 
weather  conditions  are  much  steadier  and  the 
flyer  can  devote  more  attention  to  flying  the 
machine  at  a  constant  air  speed  than  he  can 
when  very  close  to  the  ground. 

One  method  is  to  use  two  camera  obscuras, 
one  of  which  points  vertically  upwards  and  the 
other  is  set  up  sloping  towards  the  vertical 
camera.  At  one  important  testing  center  the 
cameras  are  a  mile  apart,  and  the  angle  of  the 
sloping  camera  is  45°.  By  this  arrangement,  if 
an  aeroplane  is  directly  over  the  vertical  camera 
it  will  be  seen  in  the  field  of  the  sloping  camera 
if  its  height  is  anywhere  between  1,500  and 
15,000  feet,  although  at  very  great  heights  it 
would  be  too  indistinct  for  measurements  except 
on  a  very  clear  day.  The  height  the  tests  are 
usually  carried  out  is  4,000  ft.  to  0,000  ft. 

The  aeroplane  is  flown  as  nearly  as  possible 
directly  over  the  vertical  camera  and  in  a  direc- 
tion approximately  at  right  angles  to  the  line 
joining  the  two  cameras.  The  pilot  flies  in  as 
straight  a  line  and  at  as  constant  an  air  speed 
as  he  can.  Observers  in  the  two  cameras  dot  in 
the  position  of  the  aeroplane  every  second.  A 
line  is  drawn  on  the  tables  of  each  camera  point- 
ing directly  towards  the  other  camera,  so  that 
if  the  image  of  the  aeroplane  is  seen  to  cross 
the  lines  in  the  one  camera  it  crosses  the  line 
in  the  other  simultaneously.  From  these  ob- 
servations it  is  possible  to  calculate  the  height 


of  the  aeroplane  with  considerable  accuracy;  the 
error  can  be  brought  down  to  less  than  1  part 
in  a  1,000  with  care.  Knowing  the  height,  we 
can  then  calculate  the  speed  over  the  ground 
of  the  aeroplane  by  measuring  the  average  dis- 
tance on  the  paper  passed  over  per  second  by 
the  image  in  the  vertical  camera.  If  j?  inches 
is  this  distance,  and  /  the  focal  length  of  the 
lens,  the  ground  speed  is  a?  X  h/f  feet  per  sec- 
ond. 

It  is  necessary  to  know  also  the  speed  and 
direction  of  the  wind  at  the  height  of  the  test. 
For  this  purpose  the  pilot  or  his  observer  fires 
a  smoke  puff'  slightly  upwards  when  over  the 
cameras,  and  the  observer  in  the  vertical  camera 
dots  in  its  trail  every  second.  The  height  of 
the  smoke  puff  is  assumed  to  be  the  same  as  that 
of  the  aeroplane — it  probably  does  not  differ 
from  this  enough  to  introduce  any  appreciable 
error  in  the  results.  The  true  speed  through 
the  air  is  then  found  graphically  as  shown  in 
Fig.  4.  Here  the  length  AB  represents  the 
ground  speed  of  the  aeroplane  as  measured  in 
the  camera  and  CB  represents  on  the  same  scale 
the  velocity  and  direction  of  the  wind.  The 
length  AC  represents,  also  on  the  same  scale, 
the  true  air  speed  of  the  machine. 

The  tests  are  done  in  any  direction  relative 
to  the  wind,  and  generally  at  three  air  speeds, 
four  runs  being  made  at  each  air  speed. 

The  advantages  of  this  method  are: 

(1)  Being  well  above  the  earth  the  pilot  can 
devote  his  whole  attention  to  the  test. 

(2)  Within  reasonable  limits  any  height  can 
be  chosen,  so  that  it  is  generally  possible  to  find 
a  height  at  which  the  wind  is  steady. 

(3)  It  does  not  matter  if  the  pilot  does  not 
fly  along  a  level  path  so  long  as  he  does  so  ap- 
proximately. What  is  more  important  is  that 
he  should  fly  at  a  constant  air  speed. 

(4)  It  is  not  necessary  that  there  should  be 
any  communication  between  the  two  cameras, 
although  it  is  convenient.  The  two  tracks  are 
made  quite  independently,  and  synchronized 
afterwards  from  the  knowledge  that  the  image 
must  have  passed  over  the  center  line  simul- 
taneously in  the  two  cameras. 

The  main  disadvantage  is  that  somewhat 
elaborate  apparatus  is  necessary,  but  this  is  of 


266 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


not  much  importance  in  a  permanent  testing 
station. 

There  are  often  jjcriods  in  war  time,  however, 
when  an  aeroplane  has  to  be  tested  quickly,  and 
low  cloud  layers  and  other  causes  prevent  the 
camera  test  from  being  carried  out.  It  is  then 
necessary'  to  rely  on  measurements  of  speeds 
near  the  ground  for  the  calibration  of  the  air 
speed  indicator.  In  this  method  the  aeroplane 
is  flown  about  10  ft.  off  the  ground,  and  is  timed 
over  a  measured  run.  There  are  two  observ- 
ers, one  at  each  end  of  the  course:  when  the 
aeroplane  passes  the  starting  point  the  observer 


ocfc^lowfc     0"  H<»     ground 

Thi^tto"     AC    'tyrmnft     rtic    r<ol    «^<d     oj    ftit 
Otro^owt       H\rouqK       iKc      Olf. 

sends  a  signal  and  starts  his  stop-watch  simul- 
taneously; the  second  observer  starts  his  stop- 
watch directly  he  hears  the  signal,  and  in  his 
turn  sends  a  signal  and  stoj)s  his  watch  when 
the  aerojjlanc  passes  the  finishing  point.  By 
this  double  timing,  errors  due  to  the  so-called 
"reaction  time"  of  the  observers  are  practically 
eliminated,  for  the  observer  at  the  end  of  the 
course  tends  to  start  his  watch  late,  while  the 
first  observer  Hto])H  his  late.  The  mean  of  the 
two  observations  gives  the  real  time.  Four 
runs,  two  each  up  and  down  the  course,  are  done 
at  each  air  speed,  the  pilot  or  his  observer  noting 
carefully  the  average  air  s])eed  during  the  run. 
Observations  of  the  atmos|)heric  ])ressure  and 
temperature  from  which  the  density  can  be  ob- 
tained are  also  taken.  The  average  strength 
and  direction  of  t))e  wind  during  each  trial  are 
noted  frf)m  a  small  direct  reading  (or  record- 
ing) anemometer  and  the  speed  corrected  in  the 
same  waj*  as  in  the  camera  tests.     If  there  is  a 


strong  cross  wind  the  aeroplane  may  have  to  be 
pointed  at  a  considerable  angle  to  the  course, 
and  this  makes  the  test  a  very  difficult  one  to 
carry  out  well.  Generally  speaking,  it  is  only 
reliable  when  the  wind  is  quite  light,  not  more, 
at  any  rate,  than  10  m.p.h.  Even  this  is  too 
strong  if  it  is  a  cross  wind. 

A  further  difficulty  is  that  at  high  speeds,  over 
100  m.p.h.,  an  aeroplane  may  take  quite  a  con- 
siderable time  to  accelerate  up  to  a  steady  speed, 
and  so  it  must  fly  level  for  a  long  distance  each 
end  before  reaching  the  actual  course.  At  the 
testing  station  previously  alluded  to  the  course 
is  a  mile  long,  and  there  is  a  clear  half-mile  or 
more  at  each  end,  but  it  is  doubtful  whether 
even  this  distance  is  enough  for  the  machine  to 
attain  steady  speed  before  the  starting  ])oint. 
Finally,  the  flyer  of  a  single-seater  is  generally 
too  busy  watching  tlie  ground  to  do  more  than 
glance  at  his  air  speed  indicator  more  than  a  few 
times  during  the  run.  Doubtless  it  woifld  be 
better  in  such  a  case  to  use  some  form  of  record- 
ing air  speed  instrument,  although  then  other 
difficulties  would  arise. 

Having  got  the  true  air  speed  from  camera  or 
speed  course  tests,  and  knowing  the  density  at 
the  height  at  which  the  test  was  carried  out.  we 
obtain  what  the  air  speed  indicator  should  have 
read  hy  multiplying  the  measured  air  speed  by 
the  square  root  of  the  density.  By  comparing 
this  with  the  actual  reading  of  the  indicator  we 
obtain  the  necessary  correction.  The  whole 
j)rocedure  may  be  shown  best  by  a  table  giving 
part  of  the  results  of  a  camera  test  made  at  the 
beginning  of  the  year. 

A  summary  of  the  complete  speed  tests  may 
now  be  given.  Firstly,  the  air  speed  and  en- 
gine revolutions  are  noted  flying  level  at  full 
throttle  every  2,000  feet  approximately  by  ane- 
roid. From  the  aneroid  reading  and  temjjera- 
ture  observation  at  each  height  the  density  is 
obtained.  The  reading  of  the  air  s])eed  indi- 
cator is  then  first  corrected  for  instrumental 
errors  by  adding  or  subtracting  the  correction 
found  by  calibration  tests  over  the  cameras  or 
speed  course.  This  number  is  then  again  cor- 
rected for  height  by  dividing  by  the  square  root 
of  the  density.  Tiie  result  should  give  the  true 
air  speed,  subject,  of  course,  to  errors  of  obser- 


METHODS  OF  MEASURING  AIRCRAFT  PERFORMANCES 


267 


vation.  The  numbers  so  obtained  are  plotted 
against  the  "standard"  heights,  i.e.,  the  average 
height  in  feet  corresponding  to  the  density  dur- 
ing the  test.  A  smooth  curve  is  then  drawn 
through  the  points  and  the  air  speeds  at  stand- 
ard heights  of  3,000,  0,500,  10,000,  13.000  and 
10,500  read  oft*  the  curve.  These  heights  are 
chosen  because  they  correspond  closely  with  1, 

-Figure  S  — 


2,  3,  etc.,  kilometers.  The  indicated  engine 
revolutions  are  also  plotted  against  the  standard 
heights,  because  these  observations  form  a  check 
on  the  reliability  of  the  results;  also  the  ratio  of 
speed  to  engine  revolutions  at  different  heights 
may  give  valuable  information  with  regard  to 
the  propeller. 

Table  VI  gi\es  complete  results  of  one  of  our 
tests  of  air  speed  at  heights.  The  table  refers 
to  the  same  machine  as  Table  V,  which  gives  the 
results  of  calibration  tests  of  the  air  speed  indi- 
cator. Fig.  5  shows  the  smooth  curve  drawn 
from  the  calculated  data,  the  actual  air  speeds 
calculated  from  the  observations  being  shown 
by  crosses,  while  the  observed  engine  revolutions 
at  the  same  heights  are  marked  in  by  dots.  Fig. 
6  gives  another  example,  where  the  observations 
were  very  good;  the  air  speeds  and  r.p.m.  lie 
very  closely  on  a  smooth  curve  except  at  one 
point  (about  10,000  ft.),  where  they  were  prob- 
ably affected  by  a  downward  current  of  air. 

In  a  brief  pa])er  it  is  impossible  to  do  more 
than  explain  the  more  important  of  the  "per- 
formance" tests  of  aeroplanes,  considered  solely 
as  flying  machines.  For  military  purposes  a 
number  of  tests  are  necessary,  some  of  which 
cannot  easily  be  reduced  to  figures.  Nor  can  it 
be  supposed  for  an  instant  that  the  methods 
outlined  here  are  final;  aeroplane  testing,  Uke 


all  other  work  connected  with  aeroplanes,  is  only 
in  its  infancy;  and  as  time  goes  on,  and  knowl- 
edge accumulates,  better  methods  and  instru- 
ments will  be  evolved.  There  are  some  who  lay 
considerable  emphasis  on  the  necessity  of  every 
test  instrument  being  self-recording,  and  al- 
though this  scheme  appears  at  first  sight  Uto- 
pian and  would  relieve  the  pilot  of  a  single- 
seater  of  considerable  trouble,  there  are  many 
objections  to  it  when  considered  in  detail,  not 
the  least  of  which  is  the  difficulty  of  getting  new 
and  elaborate  instruments  made  at  a  time  when 
all  manufacturers  are  fully  engaged  on  other  im- 
portant work.  When  an  observer  can  be  taken 
I  would  personally  place  much  more  reliance  on 
direct  observations  at  the  present  time,  and  one 
great  advantage  of  direct  observation  is  that  the 
results  are  there,  and  no  time  is  lost  through  the 
failure  of  a  recording  instrument  to  record,  a 
circumstance  which  is  not  unknown  in  practice. 
So  far  as  we  use  recording  instruments  we  use 
them  only  as  a  check  on  direct  observations,  al- 
though we  shall  probably  soon  adopt  I'ccording 
air  speed  indicators  for  the  calibration  tests, 
liut  whether  recording  or  direct  reading  instru- 
ments are  used,  it  is,  as  I  said  before,  the  flyer 


on  whom  the  accuracy  of  the  tests  depends.  I 
feel  that  too  great  stress  cannot  be  laid  on  tliis; 
he  is  the  man  who  does  most  of  the  experiments, 
and  like  all  experimenters  in  every  branch  of 
science,  he  requires  training  and  a  great  deal  of 
practice.  Although  the  methods  themselves 
may  l)e  greatly  changed,  this  much  may  perhaps 
be  claimed,  that  the  general  principles  on  which 
they  are  founded  are  sound,  and  will  only  be 
altered  in  detail.  The  importance  of  the  work 
can  hardly  be  exaggerated;  model  experiments 
are  notoriously  subject  to  scale  and  other  cor- 


268 


TEXTBOOK  OF  MILITARY  AEROXAUTICS 


rections,  w 

hich  if  not  carefully  scrutinized  maj' 

TABLE  V 

be  very 
full  sea 

'  in 

sleading, 
eork  that 

and  it  is 

only  by  accurate 
ope  to  maintain  a 

Calibration  Test  of  Air  Speed  Indicator  No. . . 

le  y 

we  can  h 

On. 

Machine              Date,  24/12/16 

steady 

improvement  in  the  efficiency 

of  aero- 

Measured          Corrected 

Observed 

planes. 

Measured 

wind  si)eed        true  (  =  V) 

Aneroid 

Run  No. 

ground  s])eed         and  direction       airspeed 

height 

TABLE  IV 

1 

59.1  m.p.h. 

31.0  m.p.h.  1G1.5         89.3 

5,100 

M 
ne. . 

achinc 

2 
3 

123.4      " 
62.0      " 

28.6     "           5.5         93.7 
32.3     "        168.5         93.8 

5,100 

Eng 

5,050 

Date  27/12/16 

4 

134.7     " 

32.3     "         21.0         95.6 

5,000 

Height  in 
Aneroid  ft. 

0 
1,000 
2,000 

Observed         Percentage  of 
temp.        standard  density 

36°  Fahr. 

37°      "                  101.0 

.38°      "                    97.2 

Rate  of 
Observed       climl)  in 
time        Aneroid  ft. 
0.0 

1.0                835 
2.10              735 

Density  (  =  p) 
Observed          referred  to            Observed 
temp.        standard  density        airspeed        V  X  Vp 
31                    0.879                       80.0               83.6 
31                      0.879                        85.0                87.8 

Correction 

necessary 

X3.6 

X  3.8 

3,000 
4,000 

36° 
36° 

u 

94.0 
90.7 

3.70 
5.40 

640 
560 

31                                                             ■ 
31 

0.881                           85.0                 88.1 
0.862                       86.0               88.8 

X3.1 

X  3.8 

5,000 

36° 

u 

87.4 

7.25 

510 

Mean  X  3.1 

6,000 

33° 

" 

84.7 

9.40 

450 

7,000 

30° 

It 

82.1 

11.90 

405 

8,000 

26° 

<t 

79.9 

14.25 

365 

TABLE  VI 

9,000 

22° 

u 

77.6 

17.00 

330 

10,000 

23° 

u 

74.7 

20.25 

310 

AiH  Si'EED  AT  Heights 

11,000 

21  o 

*t 

72.2 

23.60 

280 

27/12/16 

12,000 
13,000 
14,000 
15,000 

20° 
17° 
12° 

8° 

M 

69.8 
67.7 
65.9 
64.1 

27.40 
31.90 
37.90 
45.25 

230 

^95 

Aneroid 

Corresponding 
Temp.      Standard     Standard     Observed 

Corr. 
for  calil)ra- 

it 

150 
110 

height 

observed       t 

ensity         height        air  speed 

tion  tests 

3,000 

39°  F. 

.9.35               2,900         95  m.p.h. 

98 

Real  rate 

5,000 

35° 

.875               4,900         93      " 

96 

of  cliinh 

From  curve 

7,000 

30° 

.831               6,900        88     " 

91 

(corrected 

Standard 

'/r  of  stand- 

Rate of 

9,300 

24° 

.767               9,000         81      " 

84 

for  temp.) 

height 

ard  density 

Time 

climb 

10,800 
12,800 

19° 
17° 

.731             10,400        80     " 
.683             13,600         72      " 

83 
76 

8U 

1,000 

99.10 

1.30 

775 

13,800 

13° 

.664            13,400        68     " 

72 

718 

2,000 

9C.30 

2.56 

685 

15,200 

8° 

.636            14,800        65     " 

69 

623 

3,000 

93,26 

4.11 

610 

£44 

4,000 

90.25 

5.85 

545 

495 

5.000 

87.35 

7.80 

490 

Corr. 

435 

6,000 

84.50 

9.96 

435 

for 

Observec' 

380 

7,000 

81.80 

12.40 

385 

density 

R.P.M. 

FiXAL  Results  from  Cuhve 

347 

8,000 

79.16 

15.14 

345 

101  y. 

1,380 

Standard 

3» 

9,000 

76.55 

18.20 

310 

I02y3 

1,280 

height              Airspeed 

R.P.M. 

394 

10.000 

74.00 

21.61 

280 

looy. 

1,240 

3.000              103.0  m.p.h. 

1,390 

264 

11,000 

71.70 

25.41 

245 

96 

1,320 

fi.500              100.5      •' 

1,350 

316 

13.000 

69.50 

39.81 

210 

97 

1,220 

10.000                96.5     " 

1,215 

182 

1.3.000 

67.33 

.35.13 

170 

93 

1.300 

13,000                94.5      " 

1,180 

130 

14.000 

65.17 

41.88 

130 

88% 

1,180 

15,000                86.0     " 

1,160 

101 

14,500 

64.11 

46.23 

105 

86y; 

1,160 

STALLEMOMETER-.. 


HAND    CONTROL 
LEVER 


SERVO  MOTOR 


How  the  Sperry   Automatic  Pilot  is  installed   on    a    Voisin    battleplane 


CHAPTER  XXI 


THE  SPERRY  AUTOMATIC  PILOT 


Incorporating  a  Gyroscopic  Reference  Plane  and  Clinometer  for  Aeroplanes — Its 

Application  for  Military  Purposes 

By  Lawrence  B.  Sperry 


The  efficacy  of  the  Sperry  Automatic  Pilot 
in  fulfilling  its  three  important  functions,  as  an 
automatic  pilot,  a  clinometer,  and  a  gyroscopic 
reference  plane,  having  been  demonstrated  and 
established  beyond  question  by  numerous  actual 
trials,  it  will  be  interesting  to  note  the  various 
military  uses  to  which  these  functions  can  be 
put.  Let  us  consider  their  applications  sepa- 
rately, under  the  following  heads : 

1 — Reconnaissance. 

2 — Fighting  in  the  Air. 

3 — Artillery  Regulation. 

4 — Bombardment. 

Reconnaissance.  In  the  reconnaissance  ma- 
chine, the  Sperry  Automatic  Pilot,  by  relieving 
the  aviator  of  the  nervous  and  physical  strain 
incident  to  flying,  enables  him  to  rest  while  en 
route  to  the  area  of  reconnaissance,  so  that  he 
can  conserve  his  energy  for  the  more  important 


military  operations  that  he  is  shortly  to  carry 
out.  If  wounded,  he  can  go  on  or  return, 
spurred  by  the  confidence  of  knowing  that  his 
aeroplane  does  not  dejjend  upon  his  own  dex- 
terity, but  that  of  a  tireless  mechanism.  If  he 
finds  himself  suddenly  enveloped  in  a  cloud,  he 
will  be  spared  the  incident  nervous  bewilder- 
ment with  its  resultant  effect  upon  his  ability 
to  reach  the  spot  set  out  for;  in  this  connection 
he  is  able  to  check  his  position  by  reading  the 
ever  present  clinometers  on  the  gyro  unit. 

At  the  place  to  be  reconnoitered,  the  pilot-ob- 
server can  study  the  positions  below  him 
through  his  binoculars,  without  being  hindered 
by  the  increased  effort  necessitated  by  the  mo- 
tion of  a  less  steady  aeroplane,  and  without  the 
distraction  of  suddenly  finding  his  machine 
tipped  to  a  large  degree,  involving  a  consequent 
loss  of  time  in  again  finding  the  position  he  was 


269 


270 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


Hand  Control  I.ever 

observing,  and  even  though  shells  might  be 
bursting  around  him. 

He  can  take  his  feet  off  the  pedals,  perch  him- 
self sideways  in  his  seat,  and  rest  his  sketching 
board  on  the  side  of  the  machine,  while  drawing 
maps  or  making  notes;  these  actions  being  fa- 
cilitated by  the  steadiness  of  the  machine.  An 
observed  position  being  worthy  of  a  photograph, 
he  can  be  sure  of  securing  the  desired  field  in 
his  exposure,  due  to  the  machine  retaining  its 
relation  to  the  true  horizontal  and  remaining 
perfectly  steady. 

Being  the  observer,  as  well  as  the  pilot,  the 
aviator  can  carry  out,  with  an  efficiency  impos- 
sible through  the  joint  action  of  two  individuals 
acting  as  pilot  and  observer,  respectively,  those 


manoeuvers  in  piloting  that  are  necessitated  by 
the  situation  at  hand,  as  seen  through  his  own 
eyes  as  observer.  In  other  words,  there  are 
eliminated  the  inefficiency  and  loss  of  time  apt  to 
occur  when  two  men  are  employed,  due  to  mis- 
understood or  badly  carried  out  instructions  on 
the  part  of  the  pilot,  who  is  usually  above  the 
rank  of  the  observer,  and  who  may  have  his  own 
ideas  as  to  what  should  be  done. 

Owing  to  the  device,  the  pilot-observer  can 
stand  in  his  seat  to  review  his  rear  in  seaich  of 
an  enemy  machine.  If  attacked,  he  will  have 
the  advantage  of  increased  climbing  and  man- 
CEUvering  ability,  due  the  elimination  of  an  ex- 
tra passenger  and  to  the  unusual  efficiency  and 
easy  control  made  possible  by  the  never-tiring 
Automatic  Pilot.  With  this  device  the  tail  of 
the  machine  can  be  slapped  up,  in  order  to  get 
in  quickly  and  to  stay  in  the  non-fire  zone  of  the 
enemy,  who  is  perhaps  also  diving.  Thus,  with 
the  enemy's  landing  chassis  or  planes  nicely  in- 
terposed, the  pilot-ol)server  can  stand  up  and 
take  deliberate  aim  with  his  rifle  or  machine-gun, 
resting  the  rifle  on  a  part  of  the  steady  aero- 
plane, or  steadying  the  machine-gun  in  its 
crutch. 

Fighting  in  the  Air.  In  the  single-seater 
gun-scout,  the  Automatic  Pilot,  permitting  the 
selection  of  a  supersensitive,  efficient  aeroplane, 
will  convert  it  into  a  steady  gun  platform,  at  the 
same  time  bettering  the  aviator's  mananivering 
ability.     A  steady  platform  means  accuracy  of 


The  Anemometer. 


Servo  Motor — Cover  Ueniovcil. 


THE  SPERRY  AUTOMATIC  PILOT 


271 


aim  and  ease  in  reloading,  while,  should  the 
gun  become  jammed,  the  pilot  has  a  better 
chance  of  fixing  it  without  returning  to  the 
ground. 

Let  us  turn  to  the  very  powerful  gun- 
carrier,  where  it  is  thought   advisable  to 
carry  two  men,  one  sitting  in  the  nacelle, 
between  the  two  motors,  back  of  the  planes ; 
the  other  in  the  nose  of  the  same  nacelle. 
On  such  a  machine,  the  device  has  the  de- 
cided advantage  of  increasing  the  cone  of 
fire,  since  the  pilot  can  operate  a  machine 
gun  in  a  rearward  cone,  in  the  event  of 
the   enemy    outmanoeuvering   him,    or    in 
the  event  of  his  being  attacked  by  two  or 
more  machines  at  once.     On   approaching 
combat,  with  the  Automatic  Pilot  perform- 
ing the  more  irksome  task  of  correcting 
the  many  disturbances,  the  aviator,  thus 
freed,  can  scrutinize  his  enemy  with  the 
view  of  finding  the  limits  of  his  non-fire 
cone,  his   speed,  vulnerable   spots   in   the 
enemy's  craft,  and  other  points  that  will  aid  in 
planning  his  own  manoeuvers  of  attack.     This 
increased  freedom  on  the  part  of  the  pilot  gives 
him  the  chance  of  spotting  with  ease  the  differ- 
ent enemy  machines  that  he  is  about  to  attack, 
thus  preventing  him,  if  he  is  endowed  with  a 
sense  of  proportion,  from  inadvertently  getting 
into  a  position  where  he  can  do  little  or  no  good, 
since  he  knows  that  two  enemy  machines  are 
four  times  as  formidable  as  one.     It  should  be 
borne  in  mind  that  the  hitherto  great  physical 


The  Gyroscopic  unit. 

exertion  on  the  part  of  the  pilot  in  moving  large 
controls  is  eliminated. 

Regulating  Artillery  Fire.  In  the  machine 
for  regulating  artillery  fire,  the  work  of  the 
pilot-observer  is  cjuite  similar  to  that  involved  in 
reconnoitering.  Pie  will  therefore  be  aided  in 
a  like  manner,  only  instead  of  the  device  facili- 
tating the  use  of  the  sketching  board  and 
note-book,  it  aids  in  using  the  radio  or  flash 
signal. 

Bomhardment.     For  purposes  of  bombard- 


Aeroplane  equipped 
with  Sperry  Automatic 
pilot. 


272 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


ment,  there  is  the  machine  of  unusually  large  di- 
mensions, which  is  capable  of  more  nearly  equal- 
ing the  performance  of  Zeppelins,  so  far  as 
staying  in  the  air  for  long  periods  is  concerned, 
and  at  the  same  time  is  roomy  and  is  able  to 
carrj'  not  only  all  conveniences  in  the  way  of  in- 
struments, but  a  large  number  of  bombs.  For 
operating  at  decreased  radii,  there  is  a  small 
machine. 

The  evident  advantages  that  the  Automatic 
Pilot  secures  in  bombarding  operations  are  the 
following: 

The  facilitating  of  night-flying. 

The  accuracy  and  simplification  of  bomb- 
dropping. 

The  elimination  of  one  man. 

The  reduction  of  jihysical  effort  on  the  part 
of  the  pilot. 

Night  flying.  The  bewilderment  that  comes 
on  a  dark  night,  due  to  the  pilot's  imperfect 


A — Gyroscopic   I'nit.  C — Hand  Control  Lever.  E — Search   I.i(tht 

B— Air    CoinpaHs.  D— Drift   Indicntor.  V  -Aiicinomctcr. 

G— Scno  .Motor.  H— Hand  Cut  Out  Switch 


sense  of  horizontality,  is  accentuated  to  a  high 
degree  when  he  is  unable  to  secure  those  visual 
impressions  that  he  is  wont  to  use  in  the  day- 
time. xVt  night  the  pilot  nmst  depend  for  his 
sense  of  horizontality,  experts  tell  us,  on  the 
reflex  actions  of  certain  semi-circular  canals  lo- 
cated in  the  interior  of  the  ears  and  tactile  im- 
pressions coming  from  the  nerves,  particularly 
those  in  the  soles  of  the  feet  and  other  support- 
ing portions  of  the  body.  It  is  not  generally 
known  that  these  impressions  are  susceptible  to 
serious  error,  due  to  centrifugal  force  or  ac- 
celeration pressures,  which  are  cajiable  of  repro- 
ducing and  even  multiplying  gravitational  sen- 
sations, when  the  machine  approaches  an  un- 
accustomed inclination.  The  misinterpretation 
of  these  sensations  has  often  resulted  disas- 
trously. 

Bomb  Dropping.  In  bomb-dropping  it  is 
quite  needless  for  us  to  discuss  the  absolute  ne- 
cessity of  having  a  gj'roscopic  horizon- 
tal reference  plane  of  integrity  and 
accuracy,  or  to  emmierate  the  inac- 
curacies to  which  pendidums.  mercury 
tubes,  and  other  gravity  devices  are 
suscej)tible.  Oin-  experts  have  long 
ago  exi)osed  the  total  unreliability  of 
all  of  these  devices. 

The  gyroscoi)ic  apparatus  is  capable 
of  staying  within  one  quarter  of  one 
degree  to  the  true  horizontal.  A 
sensitive  aeroplane  is  held,  through 
the  intermediary  of  the  servo  motor 
and  follow-up  system,  within  three 
(]iiarters  of  one  degree  of  the  position 
oi"  this  gyroscopic  plane.  This  varia- 
tion of  three  quarters  of  a  degree 
might  seem  to  the  layman  to  be  in 
effect  a  corresponding  inaccuracy,  but 
any  one  accustomed  to  reading  a  bara- 
graj)li.  the  index  of  which  is  designed 
to  tremble  or  vibrate  constantly,  will 
appreciate  the  ease  and  accuracy  with 
which  the  pilot  bomb-dropper  can  se- 
cin-e  his  objective  in  the  mean  of  two 
extreme  positions,  especially  when 
close  to  each  other.  In  this  way  more 
accurate  results  can  be  obtained  than 
with    non-oscillating    conditions,    be- 


THE  SPERRY  AUTOMATIC  PILOT  278 

cause  this  motion  makes  all  the  parts  of  the  tudinal  wire  before  releasing  the  bomb  when  it 

follow-up  mechanism  extremely  sensitive,  as  in  reaches  and  crosses  the  lateral  wire. 

the  case  of  the  baragraph.     Furthermore,  the  The   increased   accuracy   of  bomb-dropping 

slight  motion  assures  the  operator  that  the  ap-  from  an  aeroplane  equipped  with  the  Automatic 

paratus  is  functioning  properly,  while  he  need  Pilot  is  due  to: 

only  consult  his  clinometer  located  on  the  gyro  1.  Being  able  to  get  the  aeroplane  more  ac- 

unit  to  check  up  accuracies,  curately  laterally  over  the  target. 

The  proposition  to  connect  the  bomb-sight  di-  2.  Be4ng  able  to  release  the  bomb  at  the 
rectly  to  the  gyroscopic  element  involves  ham-  proper  angular  distance  from  the  target, 
pering  its  freedom  by  friction  of  the  connecting  3.  Simplifying  the  operation  of  bomb-sight- 
links,  and  by  the  inertia  vibrations  of  the  sight ;  ing,  since  the  sight  is  held  automatically  and  ab- 
in  addition,  pressure  of  the  hand  in  making  ad-  solutely  horizontal,  thereby  allowing  the  pilot 
justments  is  likely  to  cause  inaccuracies.  It  bomb-dropper  to  focus  his  entire  attention  to 
is  always  advisable  to  leave  the  gyro  as  free  adjusting  the  sight  and  steering  the  aeroplane, 
and  unmolested  from  outside  forces  as  possi-  During  the  long  night  bombardments,  the 
ble.  elimination  of  the  extra  passenger  has  the  ad- 

With  the  bomb-sight  rigidly  fixed  to  the  side  vantage  of  either  increasing  the  radius  of  action 

of  the  machine  or  to  the  floor,  the  method  of  or  of  enlarging  the  bomb  carrying  capacity  of 

sighting  is  somewhat  as  follows :  the  machine;  while,  of  course,  in  the  event  of 

With  the  gyro  manual  control,  the  position  of  failure,  one  man  is  lost  instead  of  two.  The 
the  aeroplane  is  adjusted  until  both  clinometers  physical  work  of  which  the  i)ilot  is  entirely  re- 
read zero.  The  operator  then  secures  by  his  lieved  in  long  bombardment  trips,  especially 
rudder  the  motion  of  some  objective  in  his  field"  with  the  larger  types  of  aeroplanes,  would  fre- 
of  vision,  parallel  to  the  longitudinal  cross  wire,  quently  be  too  much  for  the  ordinary  pilot. 
During  this  time  the  deviation  angle  is  set  by  The  important  military  functions  for  which 
taking  the  usual  stop-watch  readings,  or  other  the  Sperry  Automatic  Pilot  has  been  utilized 
steps  involving  this  very  simple  operation,  demonstrate  that  it  is  essential  to  bringing  the 
The  pilot  bomb-dropper  has  now  only  to  keep  aeroplane  to  the  highest  point  of  military  effi- 
his  ultimate  objective  moving  along  the  longi-  ciency. 


The  Ilandley-l'afre  Warplane  wliicli  is  equipped  with  two  Holls-Royce   motors   of   !?80   H.P.   eaeh   and   lias   iiiounlings   for   four 
guns.    It   has  wing  span  of  98  feet  and  is  65  feet  long.     It  has  carried  2  passengers  in  one  flight 


CHAPTER  XXII 

THE  CASE  FOR  THE  LARGE  AEROPLANE 

By  F.  ITaxdley  Page,  A.F.Ae.S. 

The  question  of  aero])lane  size  is  a  most  iin-  cheaper  to  run  than  small  ones,  and  thus  prog- 
portant  one.  It  raises  the  whole  (juestion  as  to  ress  is  seen  in  every  type  of  mechanical  trans- 
whether  there  is,  or  is  not,  a  limitation  to  aero-  port  towards  the  employment  of  larj'cr  and 
plane  size,  and  therefore  whether  progress  in  larger  machines  with  a  view  to  taking  full  ad- 
construction  will  he  limited  to  improvement  on  vantage  of  the  economies  effected, 
present-day  small  tyi)es  of  machines,  or  whether  In  an  aeroplane  there  could,  however,  he  no 
there  is  an  infinite  ])ossil)ility  in  the  extension  of  advantage  in  the  use  of  large  machines  if  Ihat 
designs  to  much  larger  types.  increase  in  size  gives  a  dis])r()portionatc  increase 

It  has  heen  argued  hy  many  that,  just  as  in  weight  which  would  more  than  nullify  con- 
ships,  trains  and  other  machines  for  transport  structional  advantages,  or  if  the  large  aeroi)lane 
purposes  increase  in  size  as  years  go  on,  so  will  had  aerodynamical  disadvantages.  The  whole 
the  aero])lane  progress,  and  that  the  larger  aero-  case  needs  most  careful  examination  from  all 
plane  will  have  a  definite  place  in  the  field  of  ])oints  of  view. 

aviation.     Others  have   adopted  the  opposite  In  the  argimients  set  forth  below   I   have 

view.  endeavored  to  compare  machines  of  different 

The  general  consideration  in  favor  of  the  size  and  review  their  relative  advantages,  de- 
large  machine  is  that  although  tliere  is  a  heavier  tcrmining  first  of  all  hases  of  comparison  to 
initial  capital  outlay,  large  machines  are  nmch  cnaljle  a  true  picture  to  l)e  ohtaincd.     As  these 

cheaper    to    build,    cheaper   to    maintain    and  necessitate  the  explanation  of  a  new  method  of 

274 


THE  CASE  FOR  THE  LARGE  AEROPLANE 


275 


aerodynamical  composition  I  have  set  this  forth 
at  rather  greater  length  than  is  necessary  for 
the  development  of  the  argument  proper. 
After  a  discussion  of  the  aerodynamical  prob- 
lem I  have  dealt  with  the  effect  on  structural 
weight  of  an  increase  in  the  size  of  aeroplane, 
and  then  turned  back  to  find  the  effect  on  the 
aeroplane's  performance  of  the  weight  variation 


^^ 

/^'-^^^ 

^     vt     ^i^ 

"^      t4           %^ 

^     'tl            ^v^ 

.   r              3^v- 

^1-1                     X 

tt 

f^ 

71                 7  ' 

Jj                  tl 

j2                  Zz 

-n                 /y 

r 

0_        L_         _         i_J$Ut_        i_         S_              — 

with  size  increase.  Lastly,  there  are  a  few 
notes  on  the  large  machine  from  a  flying  stand- 
point. It  is  a  matter  of  some  difficulty  to  ob- 
tain a  true  basis  of  comparison  from  pilots' 
opinions.  Pilots  are,  as  General  Brancker  re- 
marked in  his  paper,  a  very  conservative  body, 
opposed  to  innovation,  and  the  machine  of  the 
moment's  design  is  not  necessarily  the  one  of 
the  future,  or  the  one  from  which  future  ma- 
chines will  be  developed. 

Aerodynamical  Bases  of  Comparison 

To  determine  the  calculated  performance  of 
any  machine  it  is  necessary  to  have  available 
the  wind-channel  experiments  on  the  Lift  and 
Lift/Drag  of  a  large  number  of  planes  as  well 
as  the  resistance  for  various  types  of  bodies 
similar  to  that  proposed  to  be  used.  The  curves 
of  Lift  and  Lift/Drag  are  usually  plotted  in 
absolute  units  and  in  the  form  shown  in  Fig.  1. 

From  these  wind-channel  curves  the  perform- 
ance of  the  whole  machine  is  obtained. 


After  the  general  details  of  a  machine's  de- 
sign are  settled,  such  as  the  weight  to  be  car- 
ried, the  area  of  the  planes,  etc.,  the  jjlane  re- 
sistance at  various  speeds  are  found  from  the 
Lift  and  Lift-Drag  curves.  To  these  values 
are  added  the  correct  ones  for  body  resistance, 
the  values  of  the  two  curves  added  together  and 
the  total  horsepower  required  calculated  for 
different  speeds.  When  the  engine  power  and 
propeller  efficiency  is  known,  the  curve  of  avail- 
able horsepower  can  be  plotted  and  the  ])oints 
of  intersection  of  the  two  horsepower  curves 
mark  the  limits  of  aeroplane  speed  variation. 

It  is  quite  easy  to  See  that  this  method,  al- 
though exceedingly  useful  for  any  particular 
aeroplane,  does  not  afford  a  quick  means  of 
comparison  between  a  machine  with  })lanes  of 
different  section  or  different  shape  or  loading. 
I  have  therefore  adopted  a  different  method  of 
plotting,  so  that  the  performance  of  any  ma- 
chine can  be  directly  predicted  from  the  wind- 
channel  tests,  on  the  Lift  and  Lift/Drag  of  the 
planes  used,  and  on  the  body  resistance,  the  new 
method  taking  into  account  the  effect  of  altered 
loading  or  varying  air  densities  at  various 
heights. 

I  will  deal  first  of  all  with  the  plane  calcula- 
tion. 

The  following  is  the  notation  adopted : 

V  — velocity  of  the  aeroplane  in  ft./sec. 

W — total  weight  in  lbs.  of  the  aeroplane. 

A  — area  of  main  planes  in  sq.  ft. 
— density  of  the  air  in  Ibs./cu.  ft. 

9     —32.2. 

Km — absolute  value  of  the  Lift  Coefficient. 

Kt — absolute  value  of  the  Drift  Coefficient. 

JRft — total  body  resistance  in  absolute  units 
per  ft.  per  sec.  of  the  aeroplane  con- 
sidered— i.e.,  resistance  of  the  chassis, 
body,  struts,  in  fact  all  the  resistance 
of  the  aeroplane  except  that  of  the 
planes. 

The  following  equations  maj'  be  written: 


whence 
V 


g 


_    _T_       \\V_   2. 
VKu  yJAe 


■    (1) 
•    (2) 


276 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


or 


where 


F-^a 


VKy 


•    (3) 


JF   g 

e 


Resistance  --  Kx  .  -  .  A  .  V 
9 

H.P.  =  Kx  .-  . .V^    . 

9   550 


(4) 
(5) 
(6) 


Inserting  the  value  of  V  from  equation  (2) 
above 


H.P.  =  K^/-.^„(4'.^)' 

g     550  \A      e  I 


Whence 


^^~Ky\Ky      550  \  A       e 


or 


H--=^-^;^^ 


WTiere 


550  ^  A.   e 


Summarizing 


H.P.  =  h 


Kx  FT 

Ky\Ky 


(7) 

(8) 

(9) 

(10) 

(3) 
(9) 


Instead  of  the  usual  Kx  and  Ky  curves  for  a 
plane  there  will  now  be  plotted 


1  Kx 
and  -Y^ 

Ky  Ky 


-   /-1_ 


which  is  equivalent  to  plotting  h.p.  required 
against  velocities.  A  curve  for  the  section 
known  as  R.A.F.6  and  one  for  the  section 
known  as  R.A.F.3  have  been  plotted  out  in  this 
way.  It  is  well  to  examine  these  curves  to  see 
their  general  application  before  jjroceeding  to 
deal  with  the  question  of  plane  comparison.  In 
Fig.  4  are  plotted  the  ordinary  Kx  and  K* 
curves  for  R.A.F.6  and  R.A.F.3,  R.A.F.6 
has  the  lower  value  of  Kv  maximum  and  higher 
value  for  Kv/Kx.  The  maximum  value  of  K» 
for  R.A.F.6  is  .605,  and  that  of  R.A.F.3  is  .695. 
The  result  of  this  is  reflected  in  the  curves  in 
Fig.  3  where  R.A.F.3  gives  a  slower  landing 
speed  than  R.A.F.6  for  the  same  loading.  The 
slow  si)eeds  are  related  in  the  ratio  of  the  sq. 
root  of  their  maximum  Kv  or  in  the  ratio  of  1  to 
105.  These  plotted  curves  give  them  the  rela- 
tionship between  h.p.  and  velocity  for  ecjual 
loading.  If  it  is  desired  to  know  the  actual 
speeds  obtained  with  different  h.p.  or  in  effect 
to  obtain  the  correct  scale  for  these  curves  it  is 
only  necessary  to  obtain  the  multiplying  factor, 
converting  the  horizontal  scale  into  feet  per  sec- 
ond and  the  vertical  scale  into  h.j).  This  is  done 
by  evaluating  the  constants  a  and  /;  in  equations 
4  and  10  above,  inserting  therein  the  correct 
valuation  of  JV,  A  and  e/g. 

Attention  is  drawn  to  the  fact  that  the  load- 


The  British  Handley-PHge  gun  «nd  l)oml)in((  plane.    It  hns  carried  twenty-one  passengers.     (British  Officiai.) 


THE  CASE  FOR  THE  LARGE  AEROPLANE 


277 


ing  expressed  in  weight  per  unit  of  area,  and  the 
value  of  the  density  of  the  air  expressed  as 
weight  per  cubic  unit  of  air,  appear  in  the  same 
form  in  both  velocity  and  h.]).  multiplying  fac- 
tors.    It  follows,  therefore  that  these  curves  are 


/ 

/ 

/ 

ii 

y 

p 

V 

/ 

t*- 

\ 

...'   . 

-7^ 

V 

y 

v^ 

\ 

y 

r 

,v 

^ 

^ 

^ 

^ 

*^ 

f^ 

1 

«,"/'■?.     3              I 

•        ** 

-■'■--  -' wJ 

'  "'"J 

-ioo^i «M — «i_a 

correct  for  any  loading  or  height  above  ground 
level,  the  comparison  between  the  two  being 
correct  as  long  as  the  loading  is  equal  in  both 
cases.  The  onlj'^  alteration  is  the  multiplying 
factor  of  the  horizontal  and  the  vertical  scales. 
It  is  hardly  correct,  however,  to  compare  two 
machines,  one  of  which  has  a  slower  landing 
speed  than  the  other.  For  correct  comparison 
the  slow  landing  speed  of  a  machine  fitted  with 
planes  to  R.A.F.3  section  should  be  increased 
so  that  it  is  the  same  as  that  for  R.A.F.6.  The 
area  of  the  R.A.F.3  ])lanes  should  be  decreased, 
thus  increasing  the  loading  until  the  two  slow 
speeds  are  identical.  The  loading  is  increased 
in  the  ratio  of  1  to  1.0.5.  To  compare  the  re- 
sulting curves  it  is  better  to  keep  the  multiply- 
ing factors  of  the  vertical  and  horizontal  scales 
the  same  and  alter  the  R.A.F.3  curve.  Since 
the  loading  enters  into  the  multiplying  factor 
of  the  h.p.  and  velocity  scales  equally  each  value 
of  the  R.A.F.3  curve  must  be  increased  1.05, 
both  as  regards  h.p.  and  velocity.  A  new  curve 
is  now  obtained  for  R.A.F.3  having  the  same 
slow  speed  as  R.A.F.6  and  the  multiplying  fac- 


tors being  the  same  for  both.    These  new  curves 
will  again  be  true  for  all  heights. 

We  will  take  an  actual  practical  example. 
Assume  a  machine  weighing  2200  lbs.  with  a 
loading  of  5.9  lbs.  per  sq.  ft.,  and  that  at  the 
ground  -p/g  —  425.  Then  from  equation  (4) 
a  =  50  and  from  (5)  h  =  200.  For  R.A.F.3 
the  value  of  Kv  (maximum)  is  .675,  and  of 
M^Kv  is  1.215.  For  R.A.F.O  the  value  of  Kv 
(maximum)  is  .605,  and  of  \/\/Kv  is  1.285. 
The  slow  landing  speed  of  R.A.F.6  for  the  load- 
ing of  5.9  lbs.  per  sq.  ft.  is  50  X  1.285  =  64  ft. 
per  second  or  43.5  miles  per  hour.  The  slow 
landing  speed  of  R.A.F.3  for  the  loading  of  5.9 
lbs.  per  sq.  ft.  is  50  X  1.215  =  60.5  feet  per  sec- 
ond or  41.2  miles  per  hour. 

The  new  curve  for  R.A.F.3  will  be  for  a  slow 
landing  speed  of  43.5  m.p.h.,  and  the  loading 


will  now  be 


43.5 
41.2 


X  5.9  =  6.25  lbs.  per  sq.  ft. 


Each  point  on  the  old  R.A.F.3  curve  must  have 
its  vertical  and  horizontal  value  increased  in  this 
proportion — i.e.,  multij)lied  by  1.05.  The  new 
R.A.F.3  curve  was  plotted  in  this  way. 

The  minimum  height  of  either  of  these  curves 
above  the  horizontal  is  the  minimum  h.p.  re- 
quired by  the  planes,  and,  neglecting  body  re- 
sistance, the  curve  with  the  minimum  value  will 
have  the  highest  climbing  speed.  It  must  al- 
ways be  borne  in  mind  that  the  curve  with  the 
higher  loading  will  have  the  smaller  planes,  and 
therefore  weigh  less.  Allowance  must  be  made 
for  this  in  effecting  the  comparison. 

The  three  curves  can  now  be  compared.  For 
the  same  loading  and  h.p.  available  R.A.F.3  has 
the  slower  landing  speed,  the  higher  climbing 
rate,  but  the  slower  top  speed.  If  the  loading 
be  increased  R.A.F.3  loses  its  advantage  in 
climbing  rate,  and  does  not  attain  the  same  high 
speed  as  R.A.F.6.  In  a  similar  manner  any 
other  or  more  modern  planes  may  be  compared. 

It  is  interesting  to  note,  in  passing,  that  at 
10,000  ft.  height  where  ip  =  0.55  the  value  of  a 
will  be  increased  to  59  and  of  h  to  236.  The 
effect  of  height  is  to  reduce  the  h.p.  required  for 
any  given  speed,  and  also  the  speed  range  by 
increasing  the  slow  speed.  Owing  to  the  h.p. 
scale  being  increased,  the  minimum  h.p.  re- 
quired for  flight  is  increased,  and,  therefore. 


278 


TEXTBOOK  OF  MILITARY  AERONAUTICS 


quite  apart  from  reduced  engine  h.p.,  the  excess 
h.p.  available  for  climbing  is  reduced. 

The  general  range  of  velocities  for  a  high 
speed  machine  is  from  50  to  130  m.p.h.  or  73.5 
to  190  ft.  per  sec.  In  general  the  value  of 
l/VATv  will  he  between  1.4  and  3.8.  For  a  slow 
speed  machine  flying  from  40  to  90  m.p.h.  or 
59  to  132  ft.  per  sec.  l/VKu  will  vary  between 
1.1  and  2.7.  Any  comparison  between  plane 
ounces  must  be  made  between  the  velocity  limits 
of  the  type  of  machine  considered. 

So  far  the  comparison  has  only  been  extended 
to  the  planes  of  a  machine.  The  body  of  re- 
sistance remains  to  be  dealt  with. 

The  e(juation  may  be  written : 

Resistance  =  i?t  .-.  F"   .      .      .      .    (11) 
9 


H.P.  required  —  Rb 


y 


■H 

550 


(12) 


This  equation  is  identical  in  form  with  the 
plane  h.p.  curve.  The  term  Jib  is  the  product 
of  tlie  values  of  a  resistance  coefficient  K^r^ 
and  a  body  area  S.  The  equation  may  there- 
fore be  written: — 

H.P.  required  =  Kivb  .^  .f--  V     .    (13) 
'  (/     5o0 


Whence  inserting  the  value  of  V  in  equation 
(2)  above 


H.P.  required  =^^-^    4.  I^^f    j- 


(U) 

The  H.P.  required  for  body  resistance  can  be 

plotted  to  the  same  scale  as  those  for  the  planes. 

The  values  would  be  divided  by 


W_    \W     g 
550  \  A    '  p' 

There  would  then  be  plotted  for  the  body  re- 
sistance H.P.  the  value  of: 


Kxb\KyA    •      '     •    ^^^^ 

The  h.p.  required  for  body  resistance  can  now 
be  added  to  the  plane  h.p.  curves.  Let  us  as- 
sume that  the  machine  referred  to  in  paragraph 
10  above  requires  10  h.p.  to  overcome  body  re- 
sistance at  100  ft.  per  sec.  Below  the  horizon- 
tal line  has  been  added  a  curve  of  h.p.  retiuired 
to  overcome  body  resistance,  the  scale  of  h.p.  be- 
ing the  same  as  that  for  the  planes.  The  total 
height  between  the  two  curves  for  any  value  of 
l/\/Kv  gives  the  total  h.p.  recjuired  at  that 
speed.     It  is  interesting  to  note  that  these  curves 


rartUl  view  of  tlic  Cuproiii  Tri|iliiiu-  vqui|i|)f<l  Willi  tlirct'  iiiuturi.  ut'  iW  li.|>.     This  iiiailiiiir  hns  ii  wing  spreiid  of  101   fi-ot. 


THE  CASE  FOR  THE  LARGE  AEROPLANE 


279 


are  correctly  placed  in  respect  of  one  another 
for  all  heights.  This  method  of  plotting  and 
the  curves  so  obtained  give  the  necessary  basis 
for  a  comparison  between  different  machines, 
and  reference  will  be  made  to  them  again  later 
in  the  pajjcr,  after  discussing  the  structiu'al  side 
of  the  question. 

The   Effect   of  an   Increase   in   Size  on   the 
Structural  Weight  of  Aeroplanes 

^Vttention  has  already  been  drawn  to  the  fact 
that  an  improvement  in  the  aerodynamical  qual- 


4i^ 

Ut 

V 

^    -   lU 

ti 

-tt 

Mt. 

^                                                            dnU^ 

"    ■       m 

^       tkt 

///      -  - 

—    ->tt 

1^ 

tt 

Jj 

M- 

//^ 

^■^ 

a_ U<>_. i i 

ities  of  the  machine  as  the  size  increases  may  be 
partially  or  completely  nullified  if  the  increase 
in  size  is  accompanied  by  a  disproportionate  in- 
crease in  weight.  I  will,  therefore,  accordingly 
examine  the  rate  at  which  the  weight  increases 
with  increase  hi  size. 

In  this  discussion  we  shall  leave  out  the 
weight  of  the  power  unit  comprising  engine, 
tanks,  and  fuel,  as  well  as  the  useful  load, 
whether  consisting  of  men  or  dead  weight,  such 
as  guns,  bombs,  etc.  We  will  confine  our  argu- 
ment to  the  weight  of  the  machine  structure, 
that  is,  the  portion  which  supports  the  load 
whether  on  the  ground  or  in  the  air,  with  the 
necessary  directing  surfaces  and  their  attach- 
ment to  the  main  portion  of  the  aeroplane.  In 
the  latter  category  come  the  planes,  the  fuse- 


lage, and  the  chassis,  and  these  will  be  considered 
seriatim. 

In  all  discussions  on  weight  saving  there  is 
the  general  question  as  to  the  best  utilization  of 
materials  with  the  varying  size  of  machines. 
As  the  machine  is  made  smaller,  so  eventually 
a  limit  is  reached  beyond  which  it  is  not  possible 
to  decrease  the  minimum  thickness  of  the 
material  and  retain  adecjuate  local  strength. 
Especially  is  this  the  case  in  aeroplane  work, 
where  the  members  are  usually  stressed  as 
struts,  and  for  which,  therefore,  a  hollow  tubu- 
lar construction  is  the  most  efficient  form  from 
the  point  of  view  of  mininumi  strength  for  a 
given  weight.  In  making  tubular  members, 
whether  these  be  plane  spars,  fuselage,  struts, 
or  longerons,  it  is  not  advisable  to  decrease  the 
thickness  of  the  walls  below  ^/u\  in.  to  Vi  in. 
Even  this  is  on  the  small  side  when  allowance 
is  made  for  errors  in  workmanship,  and  the  fit- 
ting in  of  the  necessary  tongue  piece  to  make 
a  secure  joint.  Considerable  economies  can  be 
effected  in  weight-saving  with  increase  in  size 
in  this  manner. 

Local  strength,  too,  determines  the  construc- 
tion of  subsidiary  parts  of  the  machine,  such  as 
the  tail  skid,  the  ribs,  tail  planes,  a  local  strength 
that  does  not  need  to  be  increased  with  inci'case 
in  size  of  the  machine,  and  here,  again,  weight 
economy  can  be  effected. 

This  better  utilization  of  material  more  than 
offsets  the  increase  in  weight  that  would  occur 
in  the  planes  provided  that  they  were  increased 
in  a  geometrically  similar  manner  and  the  load- 
ing aspect  ratio  and  section  kept  the  same.  In 
a  machine  of  which  I  can  show  you  the  })hotos 
later  the  plane  weight  per  square  foot  is  less 
than  a  small  one  for  the  same  factor  of  safety, 
and  the  total  plane  weight  is  a  lesser  percentage 
of  the  gross  weight. 

The  fuselage  weight,  owing  to  the  better  util- 
ization of  material,  is  considerably  decreased. 
The  chassis  weight  remains  about  the  same. 

The  Effect  of  an  Increase  in  Size  Upon  an 
Aeroplane's  Performance 

A  general  comparison  can  now  be  effected  be- 
tween aeroplanes  of  different  sizes  on  the  basis 


280 


TEXTBOOK  OF  MILITARY  AEROXAUTICS 


of  the  curves  described  in  Section  II,  the  total 
weight  of  the  aeroplanes  considered  being  modi- 
fied according  to  the  size  in  accordance  with  the 
conclusions  of  Section  III.  An  examination  of 
equation  Xo.  9  in  which  H.P.  equals  /;  X  Kx/Kv 
XVl/Kv  shows  that,  provided  that  similar 
planes  are  used  and  that  the  weight  per  H.P. 
remains  the  same,  the  same  plane  curve  repre- 
sents all  machines.  These  curves  as  plotted  are, 
in  fact,  curves  of  H.P.  required  per  pound 
weight  of  the  machine  for  a  given  loading  per 
square  foot.  Let  us  now  examine  the  lower 
curve  of  H.P.  required  for  body  resistance  and 
refer  to  equation  14.  Provided  that  the  area  of 
the  body  increases  in  the  same  ratio  as  the  plane 
area,  this  lower  curve  will  still,  for  any  size  of 
machine,  be  correct  in  relation  to  the  plane  curve 
plotted  above,  and  the  summation  of  the  two 
ordinates  or  the  distance  between  the  two  cin-ves 
will  represent  the  total  H.P.  required,  the  scale 
being  increased  in  proportion  to  the  increase  in 
ratio.  The  greatest  resistance  of  an  aeroplane 
is  that  of  the  body.  This,  for  smaller  shaped 
bodies,  would  increase  as  the  square  of  its  lineal 
dimensions,  whereas  its  volume  would  increase 
as  the  cube.  It  follows,  therefore,  that  the  re- 
sistance of  the  fuselage  per  unit  of  volume  will 
decrease  with  the  increase  in  size  of  the  aero- 
plane. The  lower  curve  will  have  to  be  modi- 
fied to  meet  these  changed  conditions.  This  de- 
crease in  weight  will  have  the  usual  cumulative 
effect  of  decreasing  the  weight  of  all  the  rest  of 
the  machine. 

The  curves  which  are  plotted  are  for  H.P. 
per  unit  weight  of  the  whole  machine,  and  do 
not  show  so  graphically  the  su])eriority  of  the 
large  machine  as  if  the  curves  of  H.P.  per  imit 
of  useful  weight  had  been  plotted  instead  of 
gross  weight.  In  this  case  the  curves  for  jjlanes 
and  body  would  have  their  vertical  ordinance 
increased  with  the  projjortion  of  useful  to  total 
weight.  The  balance  in  favor  of  the  large  ma- 
chine is  tiujs  apparent  directly  we  com])are  ma- 
chines of  approximately  the  same  total  weight 
per  H.P. 

The  conclusion  that  may  be  drawn  from  the 
above  theoretical  considerations  of  the  aero- 
dynamical and  structural  ({ualities  of  the  large 
machine  are  that  for  the  same  total  weight  car- 


ried per  H.P.  the  big  machine  will  effect  the 
better  performance. 

The  Large  Machine  from  the  Pilot's 
Standpoint 

There  has  been  very  much  less  experience  in 
the  flying  of  large  machines  than  with  small 
ones,  and,  therefore,  pilots  are  not  so  accus- 
tomed to  their  use,  neither  is  the  experience  wide 
enough  to  draw  general  conclusions.  It  may, 
however,  be  safely  said  that  large  machines  can 
be  built  to  operate  quite  as  easily  and  fly  with 
as  little  fatigue  as  the  best  of  the  small  ones. 
Xo  Servo-motors  are  required  for  the  controls, 
provided  the  controlling  surfaces  are  properly 
balanced.  There  is  less  work  in  flying  a  large 
machine  owing  to  the  wind  gusts,  which  seem 
large  to  a  small  machine,  being  relatively  small 
in  their  effect  on  a  large  one.  A  large  machine 
will  plow  its  way  through  gusts  without  any 
control  being  necessary,  whereas  a  good  deal  of 
war})ing  might  be  necessary  on  a  small  machine. 


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The  large  machine  can  be  handled  more  easily 
on  the  ground  and  can  alight  in  smaller  places. 
When  considered  from  the  point  of  view  of 
load  to  be  carried  or  long  distance  to  be  flown 
the  large  machine  has  it  all  its  own  way. 
^Vhere  a  large  load  is  to  be  carried  the  size  of 
the  machine  to  do  it  must  be  increased  until  the 


THE  CASE  FOR  THE  LARGE  AEROPLANE 


281 


These  men  coni])ri.sc  the  first  firniip  of  Ainerieiin  aviators  wlio  rejiresentcd  U.  S.  on  the  i-'rench  front.  In  tlie  group,  ielt  lo  right 
are:  Lieiitcnant  de  Laage,  Sergeant  C.  C.  Johnson,  New  York  City;  Corporal  Lawrence  Uunisey,  Buffalo,  N.  Y.;  Sergeant 
J.  H.  MeConnell,  Carthage,  N.  C;  Lieutenant  William  Thaw,  Pittsburgh;  Sergeant  H.  I.ufhery,  N'ew  Haven,  Conn.;  Sergeant 
Kiffin  Rockwell,  Atlanta,  Ga.;  Adjutant  Didier  Masson,  Los  Angeles,  Cal.;  Sergeant  Norman  Prince,  Boston,  and  Adjutant 
Bert   Hall,  Galveston,  Tex.     [Photo  Courtesy  N.   Y.   Times.] 


useful  load  is  sufficiently  great.  The  size  of  the 
machine  that  is  required  for  the  purpose  de- 
pends on  the  total  weight  per  H.P.  that  can  he 
carried.  There  is  here  no  (juestion  of  competi- 
tion between  large  and  small  machines,  it  is  a 
case  of  the  correct  machine  for  the  purpose. 

For  future  commercial  developments  the 
large  machine  scores  with  plenty  of  room  for 
passengers  to  sit  in  comfort,  or  mails  or  lug- 
gage to  be  carried,  and  with  its  steadier  move- 
ment will  afford  great  comfort  to  those  who 
travel  by  it.  It  is  probable  that  commercial 
aerojilane  work  will  be  undertaken  for  long-dis- 
tance journeys.  Where  delays  at  the  com- 
mencement of  the  journey  are  a  large  percent- 
age in  time  of  that  necessary  to  complete  the 
distance,  the  possible  time  taken  to  traverse  a 
given  space  may  be  as  great  or  even  greater 
than  that  taken  by  a  more  certain  means  of 
transit.  It  is  the  old  question  of  the  hare  and 
the  tortoise.  Where,  however,  the  distance  to 
be  traversed  is  great,  such  as  1,000  to  2,000 
miles,  or  with  journeys  such  as  crossing  the  At- 
lantic, the  passengers  or  mails  could  afford  to 
wait  a  day  or  two  and  will  accomplish  the  jour- 
ney far  quicker  than  any  other  means  of  transit. 
Were  the  commercial  development  of  aviation 


confined  to  journeys  of  from  50  to  200  miles, 
delays  at  starting  or  the  cost  of  organizing  to 
prevent  them  would  cause  the  aeroplane's  use  to 
be  considerably  nullified. 

It  is  this  question  of  certainty  in  operation 
that  requires  careful  attention,  for  it  is  the  one 
thing  at  the  present  time  that  the  aeroplane  re- 
quires in  order  that  it  may  take  its  proper  place 
in  commercial  work.  Engines  for  this  will 
probably  be  more  heavilj'  built  to  reduce  the 
possibility  of  breakdown,  and  multi-engine  ma- 
chines will  be  used  which  can  fly  satisfacto- 
rily even  if  one  engine  breaks  down.  Here 
again  this  points  to  the  use  of  the  larger  ma- 
chine. 

Finally,  it  must  be  pointed  out  that  the  same 
improved  performance  can  be  obtained  from  a 
large  machine,  whether  for  scouting,  fighting, 
or  weight  carrying,  provided  that  the  specifica- 
tions are  the  same  in  both  cases.  It  is  absurd 
to  compare  the  performance  of  a  weight-carry- 
ing machine  with  high  values  of  useful  weight 
per  H.P.  with  a  small  scout  of  very  small  use- 
ful weight  per  H.P.,  and  particular  attention  is, 
therefore,  drawn  to  the  methods  of  com])arison 
set  out  in  Section  II,  so  that  careful  comparison 
mav  result. 


Memoranda: 


CHAPTER  XXIII 


EVERY  MILITARY  AVIATOR  OUGHT  TO  KNOW  WHAT  HIS  OWN  AND 
THE  ENEMY'S  MACHINE  CAN  DO  AND  HOW  THEY  LOOK 

(Courtesy  of  Aerial  Age  Weekly) 


"If  you  see  an  aeroplane  that  does  not  look 
like  any  of  the  machines  shown  in  this  leaflet, 
you  are  to  make  every  eflFort  to  bring  it  down." 

This,  in  eflFect.  is  the  instruction  that  every 
French  and  Italian  aviator  receives,  not  only 
while  he  is  being  instructed,  but  periodically, 
whether  he  is  at  one  of  the  permanent  military 
aerodromes  or  temporarily  stationed  on  the 
front. 

The  Allied  Governments  found  it  necessary 
to  teach  their  aviators  and  students  all  about 
their  own  machines  and  as  much  as  possible 
about  the  enemy's  machines,  particularly  their 
appearance.  As  a  basic  principle,  the  aviator 
is  taught  that  what  does  not  look  like  one  of  the 
Allied  machines  must  be  an  enemy  machine. 
Therefore  every  effort  should  be  made  to  bring 
it  down. 

The  anti-aircraft  forces  are  taught  the  same 
thing,  and  knowledge  of  the  features  of  the 
different  types  of  aeroplanes  is  one  of  the  prime 
factors  in  making  anti-aircraft  forces  efficient. 

Lacking  that  knowledge,  the  Allied  air  forces, 
as  well  as  the  anti-aircraft  defenses,  get  confused 
and  pernn't  the  enemy  to  obtain  temporary  ad- 
vantages which  cost  the  lives  of  Allied  aviators, 
as  well  as  of  the  ])opulation  of  cities  which  are 
raided,  without  mentioning  the  strategic  advan- 
tages that  the  enemy  gains  through  gathering 
information  or  surprising  the  Allies. 

It  has  also  been  found  of  extreme  importance 
to  have  every  aviator  know  what  the  enemy's 
machines,  as  well  as  his  own  machines,  can  do. 
It  will  be  recalled  that  when  the  first  "Spad" 
appeared,  the  CJerman  aviators  did  not  give  it 
credit  for  the  speed  it  had,  so  they  ventured  too 
much  and  too  far  for  their  own  good.  The 
Cigogne  S(|uadron  and  the  Lafayette  S(]uadr()n 
were  enabled  thereby  to  maintain  supremacy  in 


the  air  and  to  bring  down  a  number  of  German 
aviators  who  did  not  know  the  fighting  charac- 
teristics of  the  "Spad." 

In  several  cases  some  of  the  machines  which 
were  thought  to  have  "  blind  sides  "  were  found 
to  have  guns  mounted  at  front  and  rear,  and 
to  shoot  below  as  well.  An  aviator  in  a  single- 
seater  fighter  would  attack  what  appeared  to 
be  a  "pusher  type,"  and  all  at  once  a  gunner 
would  emerge  from  the  small  cock-pit  and  turn 
a  stream  of  fire  on  him. 

The  United  States  is  to  train  thousands-  of 
aviators,  observers,  aerial  photograjjhers,  and 
anti-aircraft  gunners.  Many  are  taking  their 
])reliminaiy  course,  and  thousands  are  waiting 
their  turn.  Thousands  more  of  prospective 
candidates  are  not  yet  of  age,  or  have  passed 
the  draft  age  and  will  volunteer  as  they  learn 
more  about  military  aeronautics.  INIilitary  and 
aeronautic  authorities  agree  that  a  valuable 
service  can  be  rendered  to  the  nation  by  contin- 
uing to  publish  descriptions  of  machines  used 
by  the  enemy,  as  well  as  by  the  Allies.  In  the 
last  case  it  is  necessary,  of  course,  not  to  publish 
details  of  machines  which  the  enemy  has  not  yet 
caj)tured,  or  to  give  details  of  performances  of 
newly  adopted  types.  In  a  general  way,  any 
type  that  has  not  been  used  in  number  at  the 
front  for  a  period  of  at  least  two  months  must 
be  considered  as  new,  and  details  of  perform- 
ances must  not  be  published. 

The  publication  of  details  of  German  ma- 
chines is  encouraged.  The  Boche  knows,  of 
course,  all  about  his  own  types;  he  also  knows 
how  the  Allied  aeroplanes  look,  as  soon  as  one 
or  two  are  captured.  But  he  docs  not  always 
know  all  about  performances.  Thcrcfoi'e,  in- 
formation about  performances  of  new  types 
should  be  withheld. 


282 


Sopwjtli  Triplane  (British),  'i'lie  motor,  a  rotary  Clcrget,  is 
completely  surrounded  by  an  aluminum  cowling.  The  planes 
are  equal  in  span,  very  narrow  in  chord,  and  braced  by  a  single 
strut  at  either  side  of  the  fuselage.     Planes  highly  staggered. 


De  Havilland  2  (British).  Somewhat  resembles  the  F.  E.  8, 
but  the  outriggers  meet  one  another  at  the  vertical  rudder  in- 
stead of  at  the  tail  plane. 


Sopwith  single-seater  (Britisli).  Used  by  the  French  and 
British.  Also  the  Sopwith  two-seater.  Equipped  with  a  rotary 
engine,  Clerget  or  Rhone.  Identified  by  the  central  set  of 
struts,  which  stagger  outward  at  the  upper  end.  The  fixed 
triangular  fin  is  rounded  off  at  its  leading  end.  Planes  are 
considerably  staggered.  Ailerons  on  both  upper  and  lower 
]ilanes. 


Koland  two-sealcr  ((jerniaii).  The  engine  is  a  fixed  .Merce- 
des, 175  h.p.  A  machine-gun  and  bombs  are  carried.  The 
body  is  exceptionally  deep,  reaching  as  high  as  the  upper  j)lane. 
Windows  are  provided  in  tlie  sides  of  the  fuselage  for  observa- 
tion. There  is  but  a  single  interplane  strut  at  either  side  of 
the  body.  Planes  are  considerably  staggered.  Fin  and  rudder 
placed  very  high. 


F.  E.  ^b  and  2d  (British)  (Farman  Experimental).  Pusher 
type  with  a  nacelle  which  carries  a  fixed  Beardmore  or  liolls- 
Hoyce  engine.  Empennage  carried  on  four  outriggers.  Land- 
ing gear  consists  of  two  main  wheels  and  two  smaller  auxiliary 
wheels  below  the  forward  cock. 


283 


F.  F,.  8  (British).  Scout  type  single-seater  pusher  with  a 
rotary  Monosoupape-Gnome  engine.  Fin  and  rudder  area  simi- 
larly disposed  above  and  below  the  tail-plane.  Two-wlieel  land- 
ing-gear and  tail-skid  below  the  fin.  A  movable  Lewis  ma-, 
chine-gun  is  carried  on  the  deck  of  the  nacelle. 


Xioiiport.  I '.'■ed  hy  the  French,  15riti''h,  Belgians,  and  Italians.  Jlade  in  single-seater  scouts  which  have  rotary  Rhone  or  Clcrgct 
engines  and  having  a  small  wing  sjian,  and  also  two-seaters  with  fix<'d  Hispano-Suiza  engines  and  a  larger  wing  span.  Struts  be- 
tween the  planes  arc  V  shaped.  Two  sealers  have  two  sets  of  struts  at  either  side,  the  outer  sets  inclined  outward  at  the  top. 
Other  struts  are  vertical. 


Urcguet  Av.  (FrcTuhV  Has  a  fixed  Renault  engine.  Di- 
hedral on  the  upper  plane  only.  There  are  ailerons  on  the 
uj)|)er  and  lower  jilanes,  the  lower  ones  being  exce])tionally 
long  and  extending  from  the  wing-tip  nearly  to  the  body.  The 
elevators  are  lialaiucd. 


Hristol  Scout  (British).  Called  the  "bullet."  One  of  the 
fastest  scouts.  I'ses  a  rotary  Bhone  engine.  There  is  also  a 
Bristol  two-sealer  which  has  two  pairs  of  struts  at  either  side 
of  the  body.     The  two-seater  is  equipped  with  a  fi.xcd  engine. 


H.  K.  .'e  nncl  the  B.  K.  U  (British)  (Bleriot  Kxperiimnlnl). 
Thev  mnrhlnr',  are  equipped  with  fixed  H.  A.  F.  (Hoyal  Air- 
craft Factory)  engincK  with  n  four-bladed  propeller.  The 
plntM^  are  ttagfrrrrd  and  have  a  pronounced  dihedral  on  lK)th 
planes. 


Vickers  Scout  (British).  Rotary  Clerget  engine  Single 
pair  of  struts  at  either  side  of  the  body.  I'lanes  eqmd  in  area 
and  .similar  in  outline.  High  stagger.  The  engine  is  com- 
pletely surrounded  by  an  aluminum  cowling. 


284 


13.  E.  2e  and  H.  K.  8  (British).  There  Is  a  single  pair  of 
struts  at  either  side  of  the  l)ody,  in  addition  to  one  strut  which 
connects  each  pair  of  ailerons  on  upper  and  lower  wings. 


R.  E.  7  (Kcconnaissance  Kxperimental)  (British).  Upi)cr 
plane  of  greater  span  than  the  lower.  Two  pairs  of  vertical 
struts  at  either  side  of  the  body  and  a  pair  of  inclined  struts 
which  carry  the  overhang. 


Ariiistrong-Witworth  (British).  I'pper  and  lower  planes 
are  practically  similar  in  sha])e.  They  are  not  staggered  nor 
swept  bacli,  and  have  but  a  little  dihedral.  Two  sets  of  struts 
at  either  side  of  the  fuselage.  The  fin  surface  is  rather  large 
and  carries  the  rudder  quite  high. 


Paul  Schmitt  (French).  Made  in  two  types;  the  type  B.  K. 
A.  H.  (Bombardment  Henault,  Ailes  hautes)  and  the  B.  K. 
A.  B.  (Ailes  basses).  The  planes  of  this  machine  are  arranged 
to  be  altered  while  the  machine  is  in  flight,  changing  the  angle 
of  incidence  according  to  the  lift  recjuired. 


Caudron  G.  (j  (French).  Quite  similar  to  the  R.  4,  but  two 
rotary  engines  are  used.  It  has  only  four  landing  wheels  and 
a  very  narrow  lower  plane.  The  upper  ])lane  overhangs  con- 
siderably and  is  braced  by  sloping  outer  struts.  Trailing  edge 
very  flexible. 


Caudron  R.  4.  Used  by  the  French  and  British.  Twin- 
motored  tractor  type  with  a  fuselage.  The  landing  gear  is 
composed  of  a  pair  of  wheels  below  each  motor  corajtartment 
and  a  fifth  wheel  at  the  nose  of  the  fuselage. 


Aviatik  (Aviatik-u.  .Autumohil-Gesellschaft)  (German).  A 
fixed  Mercedes  17.5  h.p.  engine  is  installed.  The  familiar  ex- 
haust stock  carries  the  gases  from  the  engine  and  leads  them 
over  the  top  plane. 


Albatros  CHI.  A  German  "all  purposes"  machine  which 
carries  a  fixed  and  movable  gun.  Radiator  carried  in  the 
upper  plane.    Exhaust  pipes  similar  to  that  of  the  Aviatik. 


285 


I..  V.  O.  (Luft-Verkehrs-Gosellschaft)  (German).  Made  in  two  tj-pes:  Type  "D9"  wliioh  lias  a  175  Ii.p.  Mercedes  or  Benz  engine, 
nml  Tyiw  "1)11,"  having  a  235  h.p.  engine.  Distinguishable  by  its  "half-negative"  ailerons  and  tlie  long  span  of  the  Dll,  tlie  wing- 
cbord  of  which  is  greater  near  the  body  than  at  the  wing-tips. 


AGO  (Aktien  Gesellschaft  Otto).  A  German  single-seater. 
Rotary  Olterursol  ciigiiu-  with  propeller  spinner  or  nose-piece. 
The  vertical  rudder  is  balanced  much  in  the  manner  of  the 
French  Nicuport.  The  upper  plane  is  but  slightly  greater  in 
span  than  the  lower  and  both  planes  have  practically  the  same 
chord,  whereas  Ihe  Nieuj)ort  has  a  narrow  lower  plane. 


Albatros  D.III  (German).  Single-seater  scout  equipped 
with  a  vertical  Mercedes  engine.  A'ery  apt  to  be  mistaken  for 
a  Nieuport,  as  it  has  V  struts  and  a  narrow  lower  plane.  It 
has,  however,  a  high  vertical  fin  and  an  undcr-fin  tail-skid. 


Fokkrr  (German).  Sinple-sonter  scoiit  machine,  with  a 
rotary  OIktutscI  100  h.p.  or  a  fixed  Mercedes  170  h.p.  engine. 
Tills  ninchinc  Is  very  similar  to  the  Mornne-Saulnler,  but  Is  dis- 
tin|riii'>hflli)e  l>y  Its  commn-shnped  balanced  directional  rudder 
ami  ll«  two  pairs  of  interplnnr  strnls.  F.vidently  if'!  conslrue- 
tors  apprrriate  the  vnhw  of  adhering  to  Morane-Saulnier  lines. 


Halberstndt  (German).  Single-seater  equipped  with  a  fixed 
Argus  or  Mercedes  engine.  The  planes  are  staggered  I'e", 
and  the  upper  plane  slightly  overhanging,  thereby  differing 
from  the  Morane.  Over-all  length,  2V0'.  Span,  upper  plane, 
28' 0"  5  lower  plane.  25' 10".  Chord,  both  planes.  S' 2".  Gap. 
4' 4".  The  bidanced  tail-flaps  measure  10'  from  tip  to  tip,  and 
are  S"  4"  wide. 


iM 


Morane-Suuliiicr.  Employed  by  the  British.  A  rotary  en- 
gine is  used,  preceded  by  a  streamline  nosei)late.  The  under- 
carriage structure  resembles  the  letter  M  (initial  of  "Mora&e"). 


Martinside  (British).  Kngine  is  fixed.  Ailerons  on  uji|)er 
and  lower  planes  which  are  about  equal  in  span.  The  tail- 
plane  is  narrow  in  comparison  with  its  span. 


Moruiie-Saulnier  monoplane  (used  by  French  and  British). 
The  Parasol  type  is  equii)])ed  with  a  rotBTy  engine  and  resem- 
bles the  Morane-Saulnier  biplane.  ,.  «  ♦ 


JIorane-SAulnier  monocoques  11  and  13  niq.  It  is  often  mis- 
taken for  a  German  Fokker,  which  is  a  copy  of  the  earlier 
Morane-Saulnier. 


Farman  Freres  F.  40  (French).  A  pusher  type  biplane  with 
a  fixed  engine.  The  nacelle  is  situated  above  the  lower  plane. 
Lower  plane  has  the  same  chord,  but  about  one  third  less  area 
than  tlie  ii])i)er.     Ailerons  on  the  ui)))er  plane  only. 


De  Havilland  4  (British).  Uses  a  V-type  engine  and  four- 
bladed  propeller.  Plane's  are  slightly  staggered,  but  not  swept 
back  and  very  slight  dihedral.  Two  pairs  of  struts  used  at 
either  side  of  the  fuselage.     A  balanced  type  rudder  used. 


Salmson-Moineau  (French).  A  tractor  biplane  with  twin 
propellers  driven  by  a  single  Salmson  engine.  The  propellers 
are  carried  lietween  the  planes  l)y  means  of  X-shaped  .struts. 
The  empennage  surfaces  are  rectangular  in  shape. 


Caproni  H.  K.  P.  (Italian  and  French).  This  is  a  .'?-motored 
biplane  with  two  motors  in  tractor  position,  located  at  the 
front  of  the  fuselages,  and  a  pusher  engine  at  the  rear  of  the 
central  nacelle. 


287 


Spad  single-sciitfr  scout  (Sooictc  pour  TAviation  et  sos 
Derives).  Used  by  the  French  and  British.  All  Spads  are 
equipped  with  either  IjO  or  :200  h.j).  engines.  This  machine  Is 
easily  confused  with  the  Albatros,  a  German  scout. 


Alh.itros  D.  1.  Single-seater  scout.  (German.)  One  of  the 
fastest  of  German  aeroplanes.  It  is  equipped  witli  a  170  h.p. 
Mercedes  engine  or  a  25  h.p.  Benz  and  provided  with  two  fixed 
machine-guns  arranged  to  fire  through  tlie  propeller. 


A.K.  or  .\.1,.U.  I'renili  niacliine  for  all  uses.  Planes  are 
Jnvertly  staggered  and  the  fuselage  is  set  above  the  lower 
plane. 


Uumjiler.  (German.)  Has  the  Mercedes  17,5  h.)).  engine,  a 
fixed  and  a  movable  gun.  Radiator  semi-circular,  set  into  the 
upper  plane. 


["fc-* 


Spad  two-seater.  (French.)  Fixed  engine.  Similar  in  out- 
line (and  eonstruetion)  to  the  Spad  scout.  The  two-seater  car- 
ries a  movable  gun  at  the  rear,  in  addition  to  a  fixed  machine- 
gun  syriclironized  with  the  propeller  and  firing  directly  ahead. 


A.  E.  G.  (Allgemeine  Elektrlzitiits  Gesellsehaft.)  A  Ger- 
man two-seater  witli  a  175  h.p.  Merceiles  engine.  It  carries  a 
gun  synchronized  with  the  propeller  and  one  movable  i^t  the 
red  r. 


I.rlonl.  (Frrncli.)  A  three-pliini-  twjn-iiiotiirrd  biplane 
Imrtor  inlnji  nxr<l  rn(rlnc».  The  pinnrs  nre  sliiggered  bnek- 
ward  and  the  struts  are  run  verticolly  backward  at  the  tops. 


288 


Mnrnne-Snulnler  twin-niotored.  (French.)  This  is  n  tlircc- 
plnce  tractor  with  nacelles  cnrryinK  either  rotary  or  fixed  en- 
gines.   Two  machine-guns  are  used. 


Caproni   Triplane    (Italian).     Italy's   best   known   aeroplane,  and    the   inrp-st    triplanc    built.      It    is   (-(iiiipiicd    with   three    I'iat  or 
I.  F.  engines;  two  located  in  tractor  position  at  the  front  end  of  each  fuselage,  and  one  pusher  at  the  rear  of  the  pilot's  nacelle. 


Handley-Page  (British)  Twin-engine  bonihing  l)iplane.  One  of  the  largest  machines  built.  It  is  equi])ped  with  two  12  cylinder 
Rolls-Royce  engines.  It  holds  all  world's  records  for  large  aeroplanes  carrying  from  one  (1)  to  twenty-one  (21)  passengers.  Its 
wing-span  is  98  feet.  It  is  identified  by  its  biplane  tail,  the  motor  nacelles  mounted  between  the  planes,  the  large  overhang  of 
the  upper  plane  and  the  balanced  ailerons.  The  undercarriage  is  composed  of  four  shock-absorbing  wheels  and  a  small  tail- 
skid. 


Gotha  (German)  twin-engine  warplane.  The  machine  used  in  a  considerable  number  of  raids  on  London  and  recently  on  I'aris. 
Has  a  span  of  78  feet  and  carries  two  Benz  engines  totalling  to  4.50  in  h.p.  The  machine  bears  a  resemblance  to  the  British  Hand- 
ley-Page, from  which  data  for  constructing  the  Gotha  was  obtained,  but  it  is  a  pusher  and  the  Handley-Page  is  a  tractor.  Identi- 
fied by  its  overhanging  balanced  ailerons  (similar  to  the  Handley-Page)  and  its  usual  monoplane  tail  (differing  from  the  British 
machine  which  has  a  biplane  tail).  Three  machine  gxms  are  carried;  one  in  the  front,  one  at  the  rear  cockpit  and  a  third  below 
it,  which  can  be  fired  downward  and  backward  through  a  so-called  "gun-tunnel"  on  the  underside  of  the  fuselage. 

289 


Kokker  inunojWane  (German).  Follows  closely  the  French 
Morane,  especially  as  to  its  balanced  elevators.  Equipped  with 
a  rotary  Oberursel  80  or  100  h.p.  engine.  One  of  the  first 
German  machines  to  successfully  employ  a  mechanically  oper- 
ated machine-gun  firing  through  the  sweep  of  the  propeller. 


Br^guet  (French).  Bombing  machine  of  the  pusher  tj^pe. 
Carries  a  light  cannon  or  machine-gun.  Landing  gear  has 
tliree  wheels.     Two  vertical  fins  and  a  vertical  rudder. 


Voisin  (used  by  the  French,  British,  Belgians,  and  Italians). 
The  engine  is  a  fixed  type.  This  is  a  pusher  type  bombing 
machine,  with  a  balanced  rudder  and  a  balanced  elevator  car- 
ried on  four  outriggers  which  terminate  in  a  vertical  chisel 
«lge. 


Caudron  G.  4.  (Used  by  French,  British,  and  Italians.) 
Two  rotary  engines  are  carried  in  small  nacelles  between  the 
planes.  The  pilot's  nacelle  is  situated  between  the  motor 
nacelles.  The  empennage  is  carried  on  four  outriggers  run- 
ning back  in  line  with  the  engines,  the  lower  outriggers  acting 
as  landing  skids.  Four  vertical  fins  and  four  rudders  are 
located   al)Ove  the  tail. 


Avro  (A.  V.  Hoe  &  Co.,  Ltd.)  (British).  The  y\vro  machines  have  an  equal  upper  and  lower  wing-span.  In  the  twin  mo- 
tored m;>chlne  the  engines  are  carried  on  the  lower  plane,  with  exhaust  stacks  running  up  over  the  upper  plane.  Vertical  engines 
■re  uxed.  A  wheel  Is  located  beneath  each  of  the  two  engines.  The  two-seater  Avro  has  highly  st«ggere<l  wings  and  a  .slight 
dihrdral.  The  landing  gear  is  characteristic;  the  long  central  skid  is  located  between  the  wheels,  supporting  V  struts  at  either 
end.    The  rudder  is  of  the  balanced  "comma"  type.    There  is  no  vertical  fin.    A  rotary  engine  is  u.-sed. 


e«o 


AMERICAN  AEROPLANES,  1917-18 


AECOMARINE 


CUETI5S     TRIPLANE 


WITTEMANN- LEWIS 


McLauqtiliri 


AMERICAN  AEROPLANES,  1917-18 


WRIGHT- MARTIN 'F.B.A.' FLYING    BOAT 


McL^u^ghlin 


INDEX 


Abnormal  weather  conditions 

"Aces"    63 

Act   of  Congress    

Acetylene   process    

Ader,    Clement     

Aders,    Avion     

Adhesive    insulation    

Admiralty,    British    

Advisory    Committee   of  the   Council 

A.   E.  G 

Aerial  Airway,  Wilson 

beacon     

beacon,   French    

combat      

League    of   America    

League  of  Germany    

lighthouses     

navigation      

operations,   independent    

photography     

reconnaissance      

Reserve    Corps     

standard     

supremacy     

touring     

Aerials     142, 

Aerials,   dirigibles    

Aerials,   methods   of  suspending 

Aero    bases     

batteries     

cameras,   care   of    100, 

camera,   Pabbri    

Aero  Club  of  America 

186,    189,    199,    201,    202, 

203.    204,   206,    209,    210,    211,    212, 
214,    216,  217,   218,  219,   235,   237, 
Aero  Club: 

France     

Illinois     . 

Italy     

Aerodromes    106,    125,    128, 

Aerodynamic    comparison     

Aerodynamic   forces    

Aerofan    

Aerofoil     

Aeromap      197, 

Aeromarine      

Aero  messages    117, 

Aeronautic    appropriation    

cartograjjhy      

communication     

division,    Signal    Corps 204, 

Aeronautic  engineers    

personnel,   regulations  for  uniforms 

Aeronautics     157, 

Aeronautics  at  outbreak  of  war 

Aeronautics,    history,   U.   S.  Army 

Aero  observer    

-.70,    71,    72.    74,    91,    113.    114,    116, 
Aero- Personnel  Division.  ..  .180,   181,   182, 

Aerophotography    91,  92, 

93,   94,  95,  96-97,  98,  99,   100,  101, 

102,    103.    104,    105.    106,    107.    108, 

Aerophotography,    directions    

elevation     

interpreter     

methods      

organization     

plates     

reading     98, 

technical     

Aeroplane  aerial 

and  infantry    

armament     

armor     

batteries     

bombs     

cannon     

collapse     

communication     

contact    patrol    Ill, 

De   Laison    

Aeroplane  equipment    

fighting     

first  use  for  military  purposes 

for    spotting     

guns     48, 

installation,    wireless     

invisibility   at  night    

leading  American    

measurements   and  performances    

metal   construction    

night  flying    

night   landing    

night    patrol    

performances     

problems  of  construction    

radio  equipment        

radio  set,   Washington    


259 

64 
205 
177 
240 
240 
145 

91 
214 
266 
200 
286 
133 

63 
199 
231 
134 

23 
7 
198 
157 
212 
146 
3 
203 
143 
143 
143 

25 

74 
106 
103 


238 

203 
201 
202 
130 
275 
256 
154 
252 
202 
291 
118 
214 
200 
139 
205 
245 
190 
159 
240 
204 

142 

185 


109 

108 

101 

101 

95 

93 

104 

105 

97 

146 

121 

41 

50 

68 

94 

48 

46 

121 

121 

119 

133 

113 

231 

54 

49 

145 

125 

242 

44 

250 

125 

135 

125 

379 

245 

139 

153 


Aeroplane    equipment — Continued 

searchlight     

signals   from   ground    

testing     259, 

tests      

Aeroplanes    ....8,   44,  71,  72.  78.  84    261. 

A.   E.  G 

Aeromarine      ] .* 

Ago .43 

Albatros     44,    286.    288. 

Antoinette      

Anzani     "  '2*2*8' 

Armstrong- With  worth     .  .  . 

A.    R.    or    A.    L.    O '/.'.'.'."' 

Aviatik     '[[ 

Avro    ..!!!!..!!!!* 

Berckmans  Scout    !!'.!! 

Breese    "Penguin"     .  .  .  .  . 

greguet 15,  28,   120,'  148,'  288. 

Bristol     

Burgess 

Burgess-Dunne 207 

Caproni      •  •  •  •    ^^g' 

Caudron.15,   42,   60.   73,*i66.   139, '220' 

Continental    Pusher    

gurtisa     205,    207.    291. 

Curtis  tractor    

De   Haviland .283 

Deperdussin     ..'. 

Dorand 15 

Parman    15,   16,   42,   93*  '  i2i,"2*28  ' 

F.   E 

go^^ker     .■..■.'*.".■.■.'.' .'  .*43.'  284. 

French     

French,    Letort 

^*^^™a»    '.'..'.'.'.'.'.8q',93'. 

Gotha     

Goupy     '..'...'.. 

Halberstadt .43 

Handley  Page .'ie  "  276 

Lawsou  "M.  T.  I." 

Letorc     "iV 

L.  V.  G ^^' 

L.  W.  F '.'.'. '.'.'. '.'.'.'.]'. 

Moineau     

Martinside      !!!.!!!!..!![ 

Morane-Borel     '.'..'......... 

Morane  monoplane .  . 

Morane-Saulnier     '28Q 

Nieuport    45,   m,  228. 

Ordnance    Engineering    .... 

Paul   Schmidt 

Paulhan     "..,*' 

Pierce  Sport  Tractor 

Pilot   Observer .  .  .  . 

Pomilio  aeroplane    1  o 

R.  E.  P.  ..: ...'.'..■.'.. 

Roland    43' 

Rumpler 44] 

Salmson-Morineau 

Savary     ' 

Sopwith    [\  42,   118 

Spad    41,    44,    122^ 

Standard     

Sturtevant     

Taube     [\\[ 

Thomas    Morse    

United    Eastern     

Vickers     

Voisin    15,    228. 

Wittemann-Lewis     

Wright 204.  207, 

Zodiac    

Aero  raids  on  England 

Aero   range    finder    

Aero  searchlight    

Aero-Squadron     

Aerostatic  Section,  U.   S.  Army 

Agassiz    Geological    Museum    

Ago    

Ailerons     

Air   compass    

Aircraft  Board    

guns     

performances,    measuring     

Production  Board    201.  214,   217. 

productions    

reconnaissance     

wireless      138. 

Air  duels    53, 

fan   driven   pumps    

lines      

navigation    

offensive     

pockets     

pressure  gauges    

Air  raids,  list  of 

scout     

speed  indicator  or  meter    

293 


Akron.  0..  Goodyear  School 156 

128  Alaskan  jiea  jacket 196 

121        AlbatrOB    285,  286,  288 

267        Allen,    P.    A 282 

266       Allen,  F.  H 217 

274       Allen,    James    225 

288        Allies     91 

291  aerodromes     125 

286            aeroplanes     93 

294             aviators     90 

228            balloons     157 

244            raids,  long  distance    , 18 

285            wireless     141 

288  wireless  sets    146 

285  Alps,   crossing  by  aeroplane    6 

284       Alternator    143,   146,  148 

292  Altimeter     24,  126 

292        Altitude  photographs    108 

284  Aluminum-caustic  soda  process 174 

286  Aluminum-potassium    cyanide    process....  177 

207  America     186 

292            aviators     93 

289  "Blimp"     156,  157 

285  competition    228 

291  crankcases 257 

292  manufacturers  of  hydrogen   175 

183             training    machines    212 

287  Anchors  and  ropes   158 

228        Anemoters    165,  270.  273 

42        Aneroid    259,  262,  263 

287  Angle  of  attack 252,  254 

283  Anti-aircraft   batteries    93 

290  guns   86,  114,  125 

125             post    177 

49         Antoinette      228 

129  Appendix     158 

289        Appendix    line     158 

228        Appendix   ring    158 

286  Application  of  aircraft    238 

289  Archdeacon,    Earnest    226 

292         Arc,    potential     150 

288  Arkansas      .: 210 

287  Armatures     146 

291  Armed    photographic    planes    54 

15        Armstrong- Withworth   plane    285 

286  Army,  U.  S.  aeronautics    204 

228             Air    Service    180,    181,  182 

288  aviation    field     212 

288             Aviation  school    212 

284  aviation  school  training 185 

291  aviation   students    180 

285  balloon  school    167 

228             Deficiency   Bill    208 

292  Arnold,   Bion  J 201 

119         Arnold,    Lieut.   H.  H 204 

44        Artillery     81 

228             bombardment 122 

283             fire     71.  74 

288             fire    by    wireless     141,  149 

287  flre,    directing    72,  160 

228             regulation      269 

283  Ascensional    forces,    table     162 

288  Ascensions      83 

292        Astor,    Vincent    201 

292         Astra     228 

130  Astra  Wright    228 

292        Atlantic   Aeroplane    236,  242 

291  Atmospheric   conditions    165 

284  Atmospheric   density    259,  266 

290  Atmospheric    pressure    .'  260 

onl       -Austria     n.   m.  157 

292  Austrian  armies    112 

228        Austrian  bases    241 

20        Automatic  ball  float  valve   242 

31        Automatic   pilot    25,    27,    269,   270,  272 

128        Automobile    windlass    82 

208  Division  signal  corps   179 

163        Aviatik     293 

105       Aviation   beacons    14 

286  field.   College  Park    207 

262             mechanicians     193,  195 

272             mechanics,    insignia    190 

219              officers      195 

39             officer's  insignia    195 

259              School,    Army     212 

219             School,   Curtiss    204 

218  School    of    Military    Aerostatics    (Ground  ' 

116                     schools)      182 

139  Massachusetts  Institute  of  Technology, 

55                       Boston      182 

249  Cornell   University,    Ithaca,    N   Y 182 

200  Ohio  State  University.  Columbus,  O. .  .  182 

197  University    of    Illinois,    Urbana,    111. .  .  182 

58                  Texas   University.    Austin    182 

250  University  of  California.  Berkeley....  183 
249  Georgia  University,   Institute  of  Tech- 

1=                     nologj-,    Atlanta    188 

111  Section,    Signal   Corps    

24                   93,   180.  194,  195,  206,  207,  218 


294 


INDEX 


Section,    Signal   Corps — Continued 

Section,     Signal    Corps,     uniforms 190 

Aviation.  Training  ramp    182 

Belleville,   HI,,   oi>eratinK    182 

Fairfield,  O.  (Wilbur  Wright  Field)  oper- 
ating         182 

Port  Sin.  Okla,,  advanced   182 

Hineola.  N.  Y.,  oi>erating   182 

Mt.    Clements.     Mich.     (Selfridge    Field) 

operating     182 

Rantonl.    111.    (Chanute   Field)    0|>erating  182 

Rock.v    Mountain    Reserve    182 

San  Antonio.   Texas,   operating 182 

San    Diego.    Cal..    operating    182 

So.    Mississippi    Valley.      Under    investi- 
gation         182 

Aviation    students     187 

Aviator.    AUied    90.     91 

Aviators.  American    93.   282 

certificates     186.   187 

face    masks     191 

glovea    191.  192 

messengers     19.5 

service     192.   194 

nniforms    195 

Avion.    Clement   Ader's    240 

Avro  aeroplane    15,  298 


Back    pressure    251 

Bagnell.    Lieut.    Edward    211 

Bairn,   Chief  mechanic    211 

Baker,   George  F.   Jr 201 

Baker.   Secretar>-  of   War   298 

Balance  of  jKiwer   3 

Balancing  free  balloons t 163 

Baldwin.    Ca|>tain   Thomas   S 204 

Baldwin   dirigible    205 

Balkan    Mountains     17 

Ballast,  sacks    83 

BaOoons   83.  84.  157.  159.  163 

ballast    163 

ears    164 

capacit}-     161 

captive    74.  75,   81.  85 

Caquot     81.  160 

companies     160 

dirigible  pilot  certificates   187 

Division     179 

envelope     158.  164 

equator     158 

fabrics    164 

historic    Ill,  112 

inflation     82 

kite   76,  81.  83.  84.  87.  96,  157 

maneuver     88 

nurse 86.   160 

observation    84.   96.  156 

school.    Fort    Omaha     161.   167,  213 

Bamberger,   Lieut.  R.  S 204 

Barometer     157 

Barrage    fire     70 

Bartlett,    Capt.    Robert    A 201 

Baruch.  Bernard  II 201.  214 

Batchelder,  A.  G 201 

Battery,   hydrogen  cylinders    171 

Battleplanes     39 

B.    K.    (Bleriot    Kx|>erimeutal)     284 

Beachy  air  ships    157 

Beacon,    aerial    133 

B«a«on,  electric  flashlight   136 

Beacons,  ilermamt'    130 

Beck,   Lieut.  Paul  W 204 

Belgian  cities    25 

Belgium,   invasion    240,  241 

Bellanger,   Capt 234 

Belmont,    August     201 

Bennett.  James  Gordon   201 

Benoist  Aircraft  Co.    242 

Berlin     25 

Best,  E.  C 210 

Betbenods     high     frequency    generator.  .  .  .  143 

Bethenods  resonance  alternator    143 

Boveoa,  K.  J 211 

Biiishaiii,   Prof.  Uiram    215 

Bishop,  Oourtland  F 201 

Blades,    variable    pitch    propeller     .  .  .  .254,  255 

Bliriol,   Louis    226 

"Blimp"     157 

American     156,  161 

BriUah     173,  177 

Ooodyesr     176 

BUsa,   Un.   WiUUm   H 209,  211 

Board  of  Governors,  Aero  Club  of  America  234 

Board  of  Ordnance  and  Fortification.  .222.  223 

Body   resistance    275 

Boring  Airplane  Oo.    242 

Boelke,   CaiiMin    64,  66,  93,  241 

Borer,  F.  Jr 210.  211 

Boilinf.  Capt.  Raynal  0 20S,  210,  211 

Bomb     87 

Barlow     87 

daacription     22 

dropping 26.  SI,  289.  278 

lalliog  enrves    86 

iDiUal    vrlocitr    85 

releaaiog  drvlc*    86 

•t*!"!*     22,  278 

■  ■■iliardlng  maebioaa    64 

Boabardment   70,  269,  371,  273 

Boabardmant,  French    70 


Bombing    122 

attacks     9 

enemy    bases    4 

night   raids    125 

parties     125 

raids,    list    of    18 

raids,  long  distance    17 

damage   done    20 

incendiary     20,  34 

types   of    22.  31 

Bond.   Brig.  General  John  0 212 

Bonvalot,    Gabriel     232 

Boots,   rubber  wading    193 

Bowen.    Lieut.   T.   S 208 

Brake  horse   power    255 

Brake,    for   landing    251 

Breeches,  winter  motorcycle   193 

Breese   Penguin    300 

Brequet    aeroplane    292,  298 

BrequetMichelin  war  plane    21 

Bright,   British    authority    132 

Bristol,   Capt.  Mark  L 201 

Bristol   Scout  Aero]>lunc    292 

British   aero  photographs    93 

British    aeroplane.    Vickers   pusher  biplane  58 

airship     107 

armies 171 

army    tests     239 

blimps    173 

Commission  in   U.  S 217 

De  Haviland  scout  biplane   58 

flying   corps    217 

forces     91 

General    staff    sg 

Government      241 

Government  specification,  wireless    145 

funs     82 

Naval  Air  Service,   instruments    24 

Royal  Navy  Air  Service   76.  104 

War    Office    239 

Wright   Co 263 

Brush    discharge     145 

Buc,    France    230 

Buffalo  Aero  Squadron   210 

Buffalo,    N.   y 210 

Bulkheads      248 

Bullets  vs.  high  exjilosive  shells   51 

Bureau  of  Construction  and  Repair   214 

13urgcss    aerojilanc     207,  244 

Burgess   Dunne   aeroplane    207 

Burgess,   Dr,   G.   K 213 

Burgess,    W^    Starlmg    201 

Burns,   K.   J 210 

Byrd,  Lieut.  D.  B 211 

Cable,  A.  G 214 

Cabot,   Godfrey  L 201 

Coffyn,   Capt.  Frank  T 215 

Calcium   chloride    169 

Calibration   tests    267,  268 

California  Aviation  School    213 

Camera   91,  106,  107.  117.  264 

care   of    97 

construction     104 

Eastman  aero    102 

Pabbri    103 

Howorth     102 

long  focus   102 

stereoscopic     102 

types    of    105 

Camouflage    113 

Camshaft      257 

Canadian  photographer    96 

Chauning,   J.   I'arki:    201 

Canton,  Brigadier  General  F.  M 211 

Cauton-Unne      228 

Capacity  tanks    230 

Caproui  planes    12,   13,  50,  241,  278,  295 

Caproui  triplane   4,  13,  297 

Captain  de  Beauchamp    17 

Captain   de  Kerillis    17 

Captive    baloons    

71,  74,  76,  81,  85,  167,  159.   161 

Captive  balloons  vs,  aeroplanes   85 

Caquot   balloon    78,   81    96,   160 

Coquot,   Capt 78 

Carbcrry,  Major  Josejih  E 201,  208 

Carburetor     252 

Carburetor    headers     250 

Carlstroni.   Victor    , 211 

Carlton.    Newconib    201 

Carolian.  Lieut.  M 210,   211 

Carrizal  tragedy   209 

Carroll.  Capt.  P.  A 213 

Carter.    General     204 

Cases  for  a  balloon  inflation 165 

Case  for  large  aeroplane    374 

Cartography  aeronautic    200 

Caudron  biplane  .16.  42.  73.  139,  285-290-298 

Caustic   jiotash    170 

Ceiling  of  machine   261 

Celoria.   Senator  0 203 

Central  Powers,  wirelcaa   141 

Centrifugal    forces    266 

Oertificate.    dirigible   balloons    187 

bydroaeronlanes     188 

spherical  balloons    187 

ChamlMTlain,   Senator  George  E 218 

Chamber  of   Drputies.    French    282 

Chambers.   Capt.   W.  1 201 


Chandler,  Major  Charles  de  F 

167,  201.  204,  208,   213 

Changes   of  uniforms    J93 

Changing    speed .  .  .  .    252 

Chanute.  Octave    '    226 

Chapin.    Roy   D []    20I 

Chapman.  Lieut.  C.  C 208 

Chase,  Brig.-Gen.  John    ]  .  ! ! !    210 

Chicago  Training  Station    ..'.',   213 

Chief  Aeronautic  Engineers    245 

Contractor  of  Navy    .['.   219 

Inspector  Military  Aeroplanes    .  ...  .239,  240 

Signal  Officer    

. 181,  202,  213,  219,  223,  224,   225 

Cnristofferson     244 

Chrome  vanadium  steel   ]   250 

Circuit  of  Eastern  Prance '      232 

Clark.  Capt.  V.  E 245 

Clerget  motor    228 

Climbing     ;  ; ;    253 

Clinometer      269 

Close  formation  flying 115 

Close  reconnaissance    m 

Coast  artillery    71.   194 

Coast  defence    .'   igg 

Coast  defence,  function  of  aircraft 7 

Coast   guard    237 

Coats,  aviator,   antisinking    190 

Coats,  aviator,  leather    194 

Cochran.    Alex.    Smith     201 

Coffin.  Howard   E 201.   214,  215,   217 

College  Park.   Md 204.  205,  207,  208,   209 

Collier,  Robert  J 201,  204.  206.   212 

Colonia    Dubliin     m 

Colorado     210 

Color  filters   99 

Colt     49 

Columbus,   N.   M 208,  209,  210,   213 

Combat  machines,  tactics 54 

Commissioned   personnel    161 

Committee  on  Aeronautic  Maps  and  Land- 
ing  Places    199,  201 

Committee  on    Military  Affairs    213 

Committee  of  National  Aviation    233 

Communication   by   Wireless    139 

Compass     24 

Comjiass  bearings    117 

Conant,    W.   M 210 

Concealment     116 

Concentrating  rings    158 

Condenser  charging  device    149,   150 

Condensers,   wireless    145,  146 

Conger.    Roy   U 201 

Cougress,  Acts  of 206,  206,  222,   237 

Connecticut    210 

Connecticut  Coast  Artillery   210 

Continental    Pusher    291 

Construction  of  aeroplanes    245 

Construction  of  balloons    163 

Contact  patrol    4.    112,   121 

Contact   patrol   machines    122 

Contest   Committee,   Aero   Club  of  America  187 

Coolidge,   T.   Jefferson    209 

Cooling  system 257 

Cooperation    between    balloon    and    artillery     77 
Council  of  National  Defense  215,  235.  237,  248 

Coutelle    178 

Coyle,   Lieut.   Arthur  J 211 

Craig,  A.  M 211 

Crankshaft    bearings    257 

Culver,  Major  C.  C 140,  201 

Culver  radio  apparatus    140 

Culver  wireless  set    146,  164 

Cummings,   Lieut 210 

Ourtiss  aeroplane    .  .  .  .204,  207,  236,  244,  300 
Curtiss  Aviation  School   .  .  .  .204,  210.  211,  212 

Curtiss,   Glenn  H 201.   207.  222 

Curtiss   JN.    4-B   tractor   model    291 

Curtiss   triplane    12,   44.  291 

Curtiss   Wireless   Scout    44 

Curves  of  stress   256 


Dansette     228 

Dardanelles      91 

Dargue.  Lieut.  Herbert   76 

D'Arsonval     177 

Daucort,    Lieut 17 

Davis,    Commander   Cleland    201 

Davis,  Driggs    60 

Davison,  Lieut.  F.  Trubee 201 

Day   signalling    71 

Dayton.    Ohio    826 

Dayton  Wright  Co 244 

Decarburatiou   of  oils    378 

Deeds.  Lieut.  Col.  E.  A 301,  214 

Defensive   line    70 

Deficiency   Bill    218 

De   Havilland    288-287 

Delivering  aeroplanes  to  Europe   246 

Density    269,  280 

Density   of   gases    368 

Density    tables    868 

Department  of  Arronautios    817,  319 

Deaigner     859 

Designs  and   tests  of  suspension  patohea.  .    164 

Deatrnotivrnrs*   of    proleetUes    40 

Detached    flight    118 

Dick.   P.  R 310.  311 

Dickson,    Charles    tOl 


INDEX 


295 


.  .302 


Dickinson,    Lieut.    Oliver    P. . 

Die-forging     

Dielectric  constants    

Diffln,  F.  O 

Directing   artillery   flr^e    ^^- ^^i   isi:  li^. 
Dirigibles    125,    157,   158, 

Baldwin     

i>ilot's  certificate   

first  U.  S 

military     

naval    

wireless      

Distance   reconnaissance    

District  of  Columbia 

Dive  attack ■  ■    • 

Dodii.   Capt.  T.   F 208. 

Dodge,  W.  Earl   

Dope,    inflammable     

Drag     

Drag  roping    

Drift     

Drift    coefficient    

Drift  indicator    

Dropping  bombs    

Dubilier    condenser     

Dubilier   system     ■  ■  • 

Dubilier,    William    l**"- 

Dugouts,  German    

Dumont,    Alberto    Santos    

Duesenberg    motor     

Dusseldorf      

Duties  of  balloon  personnel •  ■  ■• 

Dwyer,  J.  T 210. 


204 
250 
146 
213 

160 
165 
205 
187 
204 
157 
157 
143 
111 
219 

65 
245 
202 

72 
275 
163 
117 
275 
272 

22 
145 
137 
253 

70 
202 
242 
7 
164 
211 


First   aero  appropriation — Contintted 

dirigibilo    204 

«i«ht     222 

gunplane    *•''' 

militar.v    aero  review    


230 


Eastman    aero   camera    

Economical  speeds    

Effect  of  size  on   performance    

Effect   of  size   on   structural   weight 

Electric  flashlight  beacon    

Electric   headlights    

Electrical  Review    

Electrolyzers    

Electrolyzers,  American   

Electrolytic    method    

Electrolytic    plant     •  • 

Electro  magnetic     controlled     oscillator .... 

Ellis,  Brig.  Gen.   H.  Handy 

Elongated   balloons    ol- 

Emergency  Air  Fleet    

Enemv    aircraft     •  • 

England    I''"' 

England,    Brig.   Gen.  Lloyd    

England,     night    flying    in     

English  wireless  apparatus    

Enlisted  aviators,  insignia 

Enlisted  men.  Aviation  section   

Begular    Army     

uniforms    

Enlisted    personnel     

Enlisted   Reserve      

Enlisted    Reserve    Proper    

Equipment,  balloons  companies 

Equipment,  cost  of 

Ericson,    P.    G i'  .V 

Essen    T,  10, 

Etampes •  •  ■  •  •  •  '  • 

European  War    -^^i.  -*=>• 

Evans,    Gen.    Robert    K 

Evolution   of   military    aeroplane    

Expansion  of  hydrogen    ....     ■ 

Experiments   at   South  Foreland    

Expert  Aviator  certificate    


102 
254 
279 
279 
136 
25 
177 
170 
171 
170 
171 
l.'Jl 
210 
159 

11 
160 
259 
210 
127 
140 
190 
193 
181 
195 
161 
1«1 
181 
164 
213 
213 

27 
287 
259 
202 
204 
168 
133 
189 


Pabbri  photo  apparatus ■  ■  .  ■  • 

Face   masks   for   aviators    191.    1«''. 

Factors  of  air  supremacy    

Factors    of    safety     •  •  •  • 

P.  A.  I.  Certificates    18"- 

F.  A.  I.  rules   

Pall  of  shots   

Pan  driven  generator   •  •  •  .  ■  ■  • 

Farman,    Henri.  15.   16.   93,  222.  282.   287. 

Parman  biplane    

Parman    reconnaissance    biplane    ....  ■  •  ■  ■ 

Favre.    A.   L :     ......  .210, 

Federal  Reserve  Officers'  Training  Camps .  . 

Federal    service     

Ferber,    Cajrt.   Louis    

Ferro-silicon     •  •  • 

Fiat    motors    '■^• 

Fibre    stress       

Field    artillery    

Field    artillery    control     

Field   companies    

Field   compression    outfits    

Field  generators    

Field    generators,    hydrogen    

Fifth    arm     ; ,  ■  ■  ■  ■■■ 

Fighting   in   the    air    57.    .2bH. 

Fighting  machines    

Fighting    pilots     

Fighting   tactics    .     

Filling  hydrogen   cylinders    

Filling     kite     balloons      

Films  vs.  plates    

Fire    control     

Fire  safety   device 

First     aero    appropriation     iiA'Vi'i' 

Aero  squadron    ^i">   ^^^ 


requisition 


222 


specifications      ^^^ 

spotting  artillery  fire    JjJ 

tractor  bijdane.  U.  S 2-7 

use  of  aeroplane  in  war   -^9 

Piske,    Rear    Admiral    Bradlej    A 202 

PiUgerald,    Capt.   S.   \V 215 

Fixed    blade    propeller     253,  255 

Fixed  camber   wings    252 

Flare    lighting     Ijf 

Flares     Ig" 

Flare    up     "° 

Flashlight    beacon     i^o 

Plexilile    pijiing     ^"1 

Flight    commanders 11^ 

Flint   Aircraft    Mfg.    Co     ^** 

Floats,    metal ^gi 

Flying    Corps    ^»^ 

instruments     iJJ 

level      261 

^r.  ;.;.•  .•.•.;.■.•;.•  .■.•.■.■;.;;i9i,ib4;  195 

suit,    summer    i^^ 

Fokker.   batteries    •  ■  .  •  •  ■  •  •  »' 

Pokker  nionoi)lane    241.   286,  ^'^^) 

Folding  landing  gear 251 

Folding,  packiug,  shipping  balloons    lOd 

Forces   of  gases    1°^ 

Formation,     aerial     fighting     Oi 

flying,    lamp    signals     68 

flying,     rules     ^» 

opposing     {|^ 

reconnaissance •    Jip 

Form  of  application.   Officers    Corps 180 

1^  Syr'". ■.::::■.■.:■.:•  264; •205.- 22^  225 

Port  Omaha    161.  167.  169.   170 

Port  Sam  Houston    •  .  •  •    •    f"8 

Foulois.  Benjamin        .  .  194.  204,  206,  208.   225 

French  aerial  beacon    133 

Aero  Club    202 

aeroplane     ^^j? 

air  raids f" 

air   raids    with   British    i» 

Army    230 

artillery    ^0 

aviation     '"; 

aviation  camp   ^^" 

aviators    j" 

balloons    . 'Ij: 

bombardment     •'; 

bombing   plane    ;>} 

French  cameras zi 

dirigible    •  ■  ■  •    l|?^ 

Flying   Corps    185.   •i"'' 

front     \l\ 

government      *^^ 

kite    balloon    g* 

landing  system ■  ■    •    1^» 

Military    competition    ^^0.   ^o" 

Ministry   of   War    ^27.   iii 

nightflying     

observers     


127 
105 
128 


German    armed    machines     47 

Automobile   Constructor's  Ass 231 

aviation    beacons    130 

bases    SI 

biplane,   A.   E.   0 42 

cities     25 

combat   machines    43 

costly    failure    240 

defensive  line    70 

dugouts     70 

government  wireless   154 

hydrogen   making    171 

hydrogen  trucks    172 

naval  bases    27 

positions     70 

Roland    jilane    46 

Rumpler  plane    ....    44 

Scout     97 

Spad     45 

Taube     154 

trenches     70 

War    Department    231 

German  wireless  apparatus    140,   141 

communication     154 

stations    152 

Gillmore,    R.    J 211 

Gliding  angle    229 

Gloves   for   aviators,   summer    192 

Gloves   for  aviators,   winter    191 

Gnome     228 

Godfrey.   Dr.  Hollis    214 

Goerz  range  finder 31,  32.     33 

Goerz   sighting   telescope    31 

Goethals,  Maj.  Gen 21'7 

Goggles     ...     192,    193,   194 

Gompers,  Samuel    < 214 

Goodrich,    C.   C 161.  210.  211 

Goodyear    Blimp     175 

Goodyear  School.  Akron,  Ohio   156 

Gorrell,   Lieut.  E.  S 208 

Gotha     14.  289 

Gotha  battleplane    79 

Gotha  biplanes    3 

Gotha  biplane,   fusilage    59 

Gotha    gunners 79 

Graduate  School  of  Military  Aeronautics.    .    185 

Graham.    Lieut.    Harry    204.208 

Graig,  AM 210 

Gravity   service   tanks    240 

Great  Britain's  Dirigibles    157 

Ground    cloth    °| 

Ground  School  of  Military  Aeronautics.  .  . .    183 

Ground    signal    sheets     121 

Guerilla  tactics    115 

Guide  and  anchor  rofie  toggle 158 

Guide  rope    lo3 

Guillaume.   Trench    5 

Gunners,  aero 71 

Guns,  largo  caliber   72 

Itewis     1^9 

mounting  on  aeroplanes 67 

mounts     54 

Vickers    73 

Guynemer,    Capt 31 

Gyroscope    efforts     247 

Gyro  manual  control   26,  - /3 

Gyroscopic    moments    256 

Gyroscopic  unit    269.  271 


pilots    

scout «' 


trenches 


107 


103 
194 
40 
46 
204 
164 
160 
154 
295 
55 
121 
211 
182 
211 
226 
176 
288 
256 
71 
245 
194 
165 
160 
165 
63 
270 
286 
64 
58 
174 
164 
108 
245 
251 
221 
257 


War    Deiiartment    226 

wireless  aii|)aratus    1*0 

wireless  trucks    144 

wireless    set     14]J 

Franco  Prussian   War    221 


Free   balloons 


163 


Free  balloon   training    161.  163 

Frost,  Cori>.  B.  C ^10 

Frost,  D.  O jll 

Fuel   capacity    ^*;? 

Fuel  leads    2j0 

Fuel    supply 


Pull  loads    254 

Funston.    Gen ^"g 

Fuselage     ■ ■'°% 

Fuselage  of  aeroplane    "o 

Gallaudet  Aircraft  Corp 244 

Garrison   uniforms    195 

Garros.  Roland    „%l 

Gary.   Elbert  H 202 

Gas  beacon    1^° 

Gas  cylinders   "  ' 

Gasoline  supply    J*J 

Gasoline     supiily     system     ^4» 

Geiger,    Lieut,  Harold    206 

General  Aeronautic  maps    J97 

General    aeroplane    ,  ,■  '. Tco 

Generation  and  compression  of  hydrogen .  .  10^ 

Generator     -69 

Generator,    wireless    1* ' 

Geographical  Congress   201 

Se?mi"ny ■::::: ; : : ; : :  .'8i.'  i^iVHo:  Vie.  233 

German    aerial    beacon    ■•■  t-?" 

aero  camera   l"l'  i"^ 

aerodromes  at  night   ••■■■■•  J^    ak'  oV  log 

aeroplanes    57.   79,   HO,   ad.  i-» 

German  ammunition    5  / 


Hagerty,  Corp.  E.  B 210, 

Halberstadt    

Hall,    Brig.-Gen.    P.   L 

Hall,    E.   S 

Hammond,  John  Hays   

Hand    air  pressure  i)umps    

Hand   control   lever    269.   270. 

HandleyPage  warplane.  .12,  47,  274,  276. 

Handley,  Sergent  Harrison   

Hangars     

Hangars,    illumination    

Handling  captive  balloon  windlass 

Haunay,    Maj.    D.    R 

Hare,  James  H 

Harriman,    W.    Averill     ■  ■ 

Hawley,   Alan   R 101,  202,   216,   217, 

Hawley.    William    

Heavier  than  air  machines   

Heinrich  Corp 

Helicopters     •  ■ 

Heligoland • -7. 

Helmets,  aviator  s    -Im^- 

Hennessey.   Capt.  Frederick  B 204. 

Henrj.   P.  J 210, 

Herbert  and  Husgen 100, 

Herck,  Capt    J 

Hertz    wireless    experiments    

Hickman,  Willis  G 

High  explosive  shells    

Hindenburg  statue   • .  .  • 

History  of  aeronautics    20b, 

History  of  U.  S.  Army  aeronautics.  .  .  .204. 

Homogeneous   dielectrics    

Honig,    Edgar    131. 

Honig   circles    

Hood    

Hoppin,  F,  L.  V 

Horizontal   reference    

Horizontal   surfaces    

Hotchkiss,    Gen 


211 
286 
210 
219 
202 
249 
272 
287 
211 
209 
127 
164 

77 
206 
202 
243 
202 
223 
244 
226 

25 
193 
206 
211 
106 
213 
141 
211 

51 
156 
211 
219 
146 
210 
131 
193 
211 
272 
247 
49 


296 


INDEX 


Hough,    Brig.  Gen.   W.   B 211 

House  Committee  on  Military  Affairs    ....  214 

Howard.  Brig.  Gen.  C.  W 211 

HoweU,  W.  T.   210.  211 

Howitzers     71 

Hoyer.  Lieut.  R.  H 211 

Hobbard.  J.  P 210.  211 

Hulbert,    Congressman    Murray 219.  243 

Humphreys.  Lieut.   Frederick  E 204 

Hutchings,  Brig.  Gen.  H 211 

Hydraulic  tests  of  gas  cylinders    163 

Hydroaeroplane  pilot's  certificate 188 

Hydrogen 84 

American  manufacturers    175 

carriers    169 

eylinders     160 

field  generators    176 

for  military  purposes 167 

from  water  gas 176 

portable  gas  j>lant    170 

Silicol  process   171 

supply    160 

trucks,    German    172 

Hydrogenite     176 

Hydolite    175 

Immelmann,  Lieut 65,  66.  241 

Imperial  Aero  Club    231 

Imperial  Automobile  Club 231 

Improvements   in   design    257 

Incendiary    bombs     20 

Incendiary  rockets    159 

Inclinometer     24,  126 

Identification  badge    . 196 

Indenting  for  stores    97 

Independent    interrupter    142 

Induction  coil    142 

Inflammable  doi>e 72 

Inflation  of  balloons    82.  163 

Insignia    190.  199 

Insignia,    sleeve    193 

Inspection,  balloon  envelope  and  net 164 

Inspection  window    158 

Installation,    wireless    138 

Instructions  for  aero  photography 91.  109 

Instructional    aeroplanes    240 

Instruments    14,   23,  24.  126 

Instruments,  sighting  telescope 31 

International    Aeronautic    Federation.  .186,  201 
International        Aircraft        Standardization 

Committee    213 

International     Convention     on     Aeronautic 

Cartography     200 

International  Geographical  Congress 201 

Invisibility   of   aeroplanes    125 

Iron    contact    process     172 

Isotta  Fraschini  motors    12,  13 

Italian   Aeronautic   Topography    203 

aeroplanes    157 

airscout    229 

Commission  on  Aeronautics  in  U.  S.    .  .  10 

raids     19 

theatre  of  war 19 

Turkish    War    232 

Italians    241 

Italy,   aeronautic  map    202 

Janney  Aircraft  Co 244 

Jenkins.   W.   C 210.  211 

Johannistal    beacon     136 

Johnson,   Corp.  Greenhow 212 

Johnson.   W.  J 210.  211 

Joint  Army  and  Navy  Committee 204 

Joy.    Henry   B ; 202 

Junior   MiliUrj'   Aviators    ..179.   186.    192,  194 

Junior  Military  Aviator's  insignia 190 

Junior   Squadron    183 

Junior   \N  ing.    instruction    184 

Kaiser's  prise    230 

Karlshrnhe  raid    17 

KeBey.  O.  E.  M 204 

Kentucky    « 210 

Kid 7.  10.  25.  27.  29 

Kiel  Canal    18.  25 

Kiel,  raid  on 30 

Kilmer.   Lieut.   W.  G 208.  215 

Kinematograph    , 96 

King  and  Queen  of  England 47 

Kirtland.    Lieut.    R.   Carrtngton 204 

Kite   balloon    71.    77.    81 

83.    84,    85.    87.    91,    06.    157.    163,  164 

Canadian     88 

eompany     83 

steering  bags 164 

truck    169 

unit    82 

Kit*  obaerrer    99 

Kitty   Hawk    226 

Klaxon  horn    121 

KnowUon.   R.  J 210.  211 

Kodja  Chai 91 

Kolbasa    86 

Konaot.   W,  W.  Jr 211 

Kruaa,  Berj.  E.  A 210.  211 

Laffoo.  Lieut. 66 

Lahm.  Maj    Frank  Vurdy 76.  202.  204,  205 

Laird  Aviation  Co. 244 

Laml>prt,  Capt.  A.  B 202 

Lallemand,    ChAries    208 


Lamp  signals,   formation  flying    56 

Landing    brakes    251 

gear      251 

ground     127.  132 

places     198.  199 

spots  for  balloons    163 

stations     127 

Langley.  C.  P 222.  223.  226 

Langley  Aerodrome    223 

Langley   Field    173 

Lanzuis  Aircraft  Co 244 

Large  aeroplane,   case  of    274 

Large    warplanes    2-41 

Large  Zeppelin  apparatus 138 

Law,    Ruth    25 

Lawson  "M  T-1"    292 

Leading  American  aeroplane 244 

Lebaudy  dirigible    157 

Lefrance,  Jean-Abel    31 

Le  Large,  Capt 172 

Leggins     193 

Lenses    104 

Letord     15.  288 

Levant  air  raids 20 

Lewis  gun 48,  52,  61,  72,  139,  208 

Life  Saving  Service    237 

Lift   coefficient    275 

Lighthouses,  aerial   134 

Lighting   aerodromes    127 

Lighting  equipment  for  aeroplanes 133 

Light  scout  aeroplanes 240 

Lighting  stand    131 

Lights  for  landing  grounds 132 

Liquid  pressure  gauge 261 

Line  of  direction    102 

Line  of  reconnaissance    Ill 

Literary  Digest    131 

Local    strength     279 

Local  or  artilh'ry  reconnaissance    112 

Lockhart,  Henry,  Jr 202 

Logj-     247 

London     126 

London  Aeronautics    127 

Long  distance  flights    187 

Lend  distance  raids    125 

Long   Island    Map    200 

Lovett,    Lieut.    Robert  A 202 

L-section .  250 

Ludwigshafen    raid    17 

L.  W.  F.  aeroplane ■ 271 

L.  W.  F.  Engineering  Co 244 

L.  V.  G 287 

Machine  guns,  mounting 67 

Magnetic   forces,    wireless    151 

Magnetos    257 

Major    aerial    operations     241 

Mann,  Congressman  James  R 213 

Manoeuvering  and  pressure  valves 164 

Manoeuvering   valve    163 

Map  holder,   Sperry    201 

Maps 74.  75,  91,  113,  197 

Map  with  photograph  of  route    200 

Marconi    Co.,    wireless     155 

Marconi  wireless  experiments 141 

Mariner's    chart    197 

Martin   aeroplane    207 

Martin,  Dr.  Franklin    214 

Martinside     286 

Massachusetts  Institute  of  Technology   ....  216 

Maurice  Farman  biplane,  wireless    147 

Mauser  Work.s,    Oberndorf    IS 

Maximotor    244 

Maxim,    Sir   Hiram    48.  222 

McClasky,  Lieut.  J.  W 204 

McCormick.    E 210 

McCormick.  Harold  F 202 

McCoy,   Capt.  J.  C 202 

McDaniels,   Lieut.   Curry  A 211 

McGregor,    J.    S 213 

McMillin,    Capt.    Ralph    E 210 

McMillin,    Emerson 202,    209,  232 

McMullen.    Lieut.  Byron    211 

Mean   density    260 

Mean    pressure     260 

Mean   temperature    260 

Measuring    aircraft    performances 259 

Mechanical  interrupters   150 

Mechanics  of  the  aeroplane    238 

Mercedes   engines    3,  288 

Merrica,   P.  D 213 

Messengers,    motorcycle    194 

Messerschmitt.  A 173 

Metal  construction  for  aeroplanes 250 

Metal  floats    251 

Meteorology    166 

Mexican  campaign    206.  208,  231 

Mexico,  punitive  expedition Ill 

Mexican   War    204 

Meyers,    Eugene.    Jr 202 

M.    F.   P.  Aero  Co 244 

Micbelln.   M 47 

Mignot,    Lieut.    M 213 

Military   aeroplanes    245.  240.  257 

afroplanes,    evolution    222 

aerodromes    106,  135 

arroKtntics    157 

aviftlors    179.   1»2.  194 

aviator's    insignia    190 

dirigibles    167 

loa<f 246 


Military    aeroplanes — Continued  O 

Qiaps     197 

observation    balloons    158 

Military   operations    .91,  197 

operations  with  aircraft 5 

service    157 

seaplane  supply  system 249 

Miller,   Capt.  James  E 202.  214 

MiUerand,    M 233 

Millevoye.    M 233 

Milling,   Lieut.  T.  de  Witt 204.  208 

Mineola,    Long  Island    216,  211.  215 

Minnesota     210 

Moineau     47 

Monastir,    photo    22 

Monoplane,    Morane    287 

Montariol.    Lieut 185 

Montgomery,   R.   L 214,  215 

Morane-Saulnier    207,  241,  286-287-288 

More.  Morgan    211 

Morse  code    77,   121,   128.  134 

Morse,   D.  P 210,  211 

Motion    picture  films    108 

Motor   Boating    29 

Motor,   Baerdinorear  or  Clerget    43 

Competition,  Kaiser's    230 

Motor,  Canton-UnnS 39 

car   wireless  station    138 

Isotta   Fraschini    50 

Servo     269.  270 

transports     169 

trucks     160 

truck    operation    164 

Fiat     12 

Rolls-Royce     274 

(See  Textbook  of  Naval  Aeronautics). 

Mouillard     226 

Mount    Cornillet    91 

Mufflers,   aviator'.s 195 

Muffler   requirements    251 

Mulock,  Lieut.  R.  H 134 

Multiplane    222 

Munich  raid    18 

Mustin,   Lieut.   Commander  Henry  C 202 

Muzzle  velocity    52 

Nash,  Brig.-Gen.  Van  Holt 210 

National   Advisory    Committee   on   Aeronau- 
tics        214 

Aerial  Coast  Patrol  Commission 245 

Aeroplane   Fund    235 

Guard  of  New  York    209.  213 

Naval  dirigibles  (See  Textbook,  Naval  Aero- 
nautics ) . 

maps     197 

observers    91 

Navarre,   Lieut 64.  241 

Navigating      instruments      (See      Textbook, 

Naval   Aeronautics)     126 

Navigation   lights    25 

Navy  Department 204 

Navy   Department,    Pensacola    173 

Nebraska    210 

Net  toggles    158 

New  Hampshire    211 

Newport  News,   Virginia    210 

Newton,   Byron  R 236 

New  York    210 

New  York  National  Guard    209 

New  York  to  Albany  map 198 

New  York  to  Chicago  map 199 

New  York  to  Newport  News  map 199 

New  York  to  San  Francisco  map 199,  200 

New  York  World 212,  236 

Nieuport  aeroplane 4.  7,  121.  284 

Night  bombing 21.  23 

flying  ..25,  73,  125,  127,  130,  131.  133.  272 

landings 126.  128.  135 

landing  sights 24 

lights     132 

patrol     125 

operation  of  aeroplanes 126 

raids    10,  125 

signalling    71,  132 

use  of  balloons 159 

Nocturnal  flyers    130 

Non-recoil  gun  mounts 64 

Normal  atmosphere 261 

Norris,  G.  L 213 

North  Carolina   211 

North    Pole    200 

North   Sea    136 

Noyes,   Corp.  D.  R 210 

Nurse,  balloon 86 

Observation  balloons  86»  06,  156.  157.  158.  160 

"Observe  for  line"    75 

"Observe   for  range"    76 

Observed  air  B))eed    266 

Observer,    wireless 147 

Observer,   wircleas  signaling    ■  .  .  149 

Observers    71.  72.  74.  84.  87.  91. 

99.    113.    114.    116,    UH.    119.    122.  126 

Odell,  Quartermaster  Serj.  W.  T 210,  211 

Offensive,   fighting  tacticM      68 

Officers*    Reserve    Conw.    form    of   applica- 
tion       180 

Oil  consumption    S80 

OUIng  system    867 

Ohio     .: 211 

Oklahoma    211 


INDEX 


297 


Olyphant.  R.  M.  Jr 210.  211 

Omaha     163,  204 

One-place    machiniw    246 

Operation   of   balloons    213 

Opposing  formation    115 

Orders  of  reconnaissance 116 

Ordnance    Engineering     291 

Oregon     211 

Organization  and  Training  Division 182 

Organization  of  balloon  companies   164 

Osborn.    Lieut.    B 210 

Oscillation    247 

Oscillating  circuits    141,   145.   149.  1.51 

Ostend    7.  27.  91 

Oversea  reconnaissance    246 

Pallone-Cervo  Volante    85 

Palmer.  George  M 210 

Pan  Americanism    222.  237 

Pan  American  Aeronautic  Exposition    ....   222 

Paper  kites   159 

Parabellum  gun    48 

Parachute     87,     88 

Parasite    resistance    245 

Paris    125,   241.   282 

Aero   Show    232 

•Madrid   Race    232 

■Rome   Race    232 

siege     Ill 

Parke.    J.    D 202 

Patrolling  aeroplanes    110.  125 

Paul    Schmitt    285 

Payne,  S.  G 213 

Peary,  Rear  Admiral  Robert  E 

201.   -'IT.  238,   239 

Pedals    270 

Pendulums     272 

Pensacola     173 

Performance  curves    252.  253.  254 

Perfetti,  Maj.  R 10.      11 

Perkins,    George    W .  .    202 

Permanent  air  routes    197.   199 

Permeability  of  gases   164 

Parmelee.  P.  0 204.  206 

Pershing.  Gen.  John  .J 111.   128.  20K.  209 

Personnel  Division.   U.  S.  Signal  Corps...    180 

Persuit   or  combat   machines    43 

Petit  Journal    233 

Petit  Parisian    233 

Petrol    consumj}tion    264 

Petrol  flares   127,   133 

Peugeot    47 

Philippines     204 

Photographic  Corps    93 

machines    4 

maps    91.   200 

maps  of  sectors    198 

positions     105 

Photographing  enemy  positions 4 

Photography    91 

aero    198 

altitude    108 

balloon    164 

Pilot 117.    130.   270,   280 

balloon    158 

certificate     204 

certificate,    spherical    balloon.s 187 

hydroaeroplane    187 

cockpit    240 

observer    269 

Pilot    signals     129 

Sperry    automatic     269 

Pistol  camera    101 

Plates  vs.    films    109 

PlessisBelleville    66 

Pomilio,  Capt.  A 213 

Roncagli.   Commander  Giovanni    203 

Poor,   Prof.   Charles   L 202 

Portable   aerial   beacon    133 

field  generators   160 

gas    beacon    133 

hydrogen  gas   plant    170 

wireless  sets    140 

Position    41 

Position  of  aeroplane  guns   68 

Post,  Augustus    63,  81,  217 

Potomac    River    222 

Powerplant    245 

Preliminary  flying  test,   U.  S.  Army 189 

Preliminary  Training  Tractor 242 

Prentice.    W.   F 213 

President  Manuel  Estrada,    of  Guatemala   .    201 

President   Wilson    214,    218.   219.  230 

Primary  Military  Tractor    244 

Prince  Henry  of  Prussia   230,   232 

Prince,  Lieut.    217 

Prince.   Norman    241 

Principles  of  aerial  combat 63 

Problems  in  aeroplane  construction 245 

Problems  in  aerophotography    91 

Propellers,  fixed  blade 253.  255 

for  variable  pitch  angle 253,  255 

stresses     255 

variable  pitch    253 

Properties  of  hydrogen    167 

Property  damages  from  balloons 164 

Protecting    aeroplanes     121 

Protecting  reconnaissance  machines 115 

Pulitzer.   Ralph    202.  212 

Purifying  hydrogen    169 

Pursuit   machines    40.  246 


Pushers    247 

Quartermaster  Corps    194 

Rader,   Lieut.  Ira  D 208 

Radian     256 

R.  A.  F 260,  277 

Raiding    39 

Raids    79 

maps    197 

night    125 

Zeppelin     125 

Radio  Communication    139 

Division.  U.  S.  Navy   155 

engineers    148 

for  aeroplanes 139 

frequencies     152 

set.   Washington    154 

Radius  of  action   253 

Railway  truck  for  hydrogen   174 

Reber,  Maj.  Samuel 202,   204 

Receiving  station,  wireless 151 

Receiving  trucks,  wireless   144 

Reconnaissance   Ill,  112,  245,  269 

aeroplane 240 

machines     115,  121 

patrol     114 

Reconnoitering    4 

Red  sack  for  rippingjianel  cord 158 

Reed,  Lieut.  Charles 215 

Reference   plane 269 

Regular  air  lines    200 

Regular  Army   179.  180.   186 

Regulating  artillery  fire 271 

Regulation    for    uiiiform.s    of    U.    ,S.    Aero- 
nautic  personnel    190,   193 

Relief  map 179 

Renault  motor    15,  222 

Rej)resentativo  American  aeroplanes 244 

Reserve  Military  Aviators 179,   186 

Reserve    Officers'    Aviation    Section.    Signal 

Coriis    214 

Reserve  Officers  (flying  duty)    181 

Reserve  Officers  (non-flying  duty)    181 

Resistance    247 

Reverse  bending    256 

Revolving  commutators    152 

Reynolds,  C.  H 210,  211,  234 

Ribel,   Oscar    63 

Reid,  Ogden  Mills 202 

Rigging  truck   82 

R.  M.  A.  certificates 189 

Rip  panels    163.  264 

Roberts  motor 244 

Robinson   motor    244 

Rockwell.   W.   L 210,  211 

Rogan,  Brig.  Gen.  C.  li 211 

Rogers,  A.  B 213 

Roland     283 

Rolls-Royce  motors 288 

Roseuwald.  Julius 214 

Rotation  in  pitch    256 

Rouzet    146 

Royal  Aircraft  Factory   13.  259 

Royal  Air  Service   13.      15 

Royal  Flying  Corps   6,  15.  77.  259 

Rubber  wading  boots 194 

Rumpler    47.  288 

Russel,  R.  F 210.  211 

Russia     157.   174 

Russian  air  scout 120 

balloons    86 

machines,  Sykorsky 55,  240 

Ryan,  Thomas  F 202 

S.  A.  E 250 

Safety   device    251 

Safety   point    92 

Sales,  Brig.  Gen.  W.  W 212 

Salmon.  Corp.  H.  H 210,  211 

Salmson-Moinian     287 

Salonika   9,  10,  17,  33,   125 

San    Antonio    204,  208 

San  Diego 204,  205,  211,  213 

San  Marsano,  Charles  de 201 

Santos  Dumoot,  Alberto 226 

Sausage    81,  84,  159 

Schools,   Curtiss  aviation    204 

of  military  aeronautics 182 

Schuckert   generators    171,   172 

Scientific   American    178 

Scott,   Gen 202 

Seaplane  (See  Textbook  Naval  Aeronautics)   248 

Searchlights    126,   127,  128,  136.   272 

Searchlight  signaling    128 

Second  and  Third  Aero  Squadrons 213 

Secretary  of  Aero  Club  of  America    187 

War.  U.  S 190.  206,  208,  217,  218,   219 

Seeing  wireless  signals 138 

Seiberling,   Frank  A 202 

Selfridge,   Lieut.  E 204 

Selfridge  Field    224 

Semi-rigid  dirigibles   157 

Senior   Squadron    183 

Senior  Wing,  instructions   184 

Service  cap    195 

Servo  motor   270,  288 

Shapes  of  balloons   164 

Sharp,   Ambassador    202 

Shaw.  Edwin  C 202 

Sheldon,  Lieut.  Harold  P 212 


Sbeppard-Hulbert  Bill    217 

Sheppard,   Senator  Morris    219.  243 

Sherman.  Lieut.  William  G 204 

Shinnecok    244 

Shoes,  aviator,   winter    198 

Shooting  through  iiropelters    68 

Short  range  reconnaissance 246 

Shrapnel     71,     72 

Sideslips     181 

Siege  warfare    160 

Siemens  Bros.  Co 171 

Signal  codes    128 

Signal  Corps  .161,  175,  182.  192.  193.  194 

204,  206,   207,  212.  213.   219,  223.  245 

Signal  Enlisted  Reserve   181.   182 

Signal  Enlisted  Reserve  Corps   179 

Signal    Equipment    132 

Signaling    71.  72.  77,  80,     86 

Signaling  by  searchlight   128 

Signaling  to  aeroplane 121 

Signal  Officers'  Reserve  Corps  ...179.  182,  211 

Signals  at  night 133 

for  night  flyers   131 

from   balloons    160 

Silencers    21 

Silico  Acetylene  process 178 

Silicol  process,  hvdrogen   171 

Simon.  E.  J 155 

Simmons,   Lieut.  H.  H 215 

Shock  absorbers  for  landing  gear 251 

Shoulder  loops    190 

Skill   in  piloting   41 

Skill  in  taking  photos    104 

Sykorsky     55 

Small  power  wireless  sets    140 

Smith,   P.  D 210.   211 

Smith.   Serg.  L.  V 210 

Sofia     17 

Somme.  jihoto   5 

Sopwith  aeroplanes    ...  .60.   118.  241,  244,   283 

Sopwith  factories    47 

Sorbonne     233 

South  Foreland  experiment      133 

Spads  aeroplanes 241.  288 

Spark  electrodes   147 

Spark  gap    140,   141 

Special  aeronautic  maps    197 

Specifications  for  uniforms    190 

Speed     40 

Speed  course  tests    266 

Speed  indicators 267 

Speed  in  tactics    64 

Speed  scout   242 

Sperry  automatic  pilot 25.  269,  271 

bomb  sight    19,     35 

Gyroscope  Co 155 

Lawrence  B 25,  199.  202.  210.   269 

map  holder    201 

Speyers,   J.   R 211 

Spherical   balloons    81.    158.   159 

Spherical  balloon  pilot's  certificate   186 

Spirit  level  lateral  inclinometer    24 

Spotting  aeroplanes    54 

Spotting  artillery  fire    71,  72.  73.  77,   153 

Spreading  balloon  envelopes    163 

Squadron    commanders    113 

Squadron    flight    117 

Squires.  Brig.  Gen.  George  O 

202,  204,   205,  206.  209.   214.  215,   217 

Stability     239 

Stallometer     269 

Stamford    210 

Standard  aeroplane    244-292 

Standard  aeroplane  aerial   146 

Standard  aero-squadrons   186 

Standard  atmosphere    261 

Standard   density    260.   261.   268 

Starting   field    245 

Starting  motor  for  engines    248 

Statoscope    158.  262.  263 

Steel  aluminium  alloy 250 

Steel  battleplane   244 

Steel  spring  shock  absorber 251 

Steel   tractor    244 

Steeple   banked   turn    256 

Steinmetz,  .Joseph  A 217 

Stephens,  James  S 202 

Sterling  Telephone  Co 140 

Stevenson,    Serg.    J.    H 210,   211 

St.  Louis  Balloon  Race   101 

Stockton.  P.  R 211 

Strategical-reconnaissance    machines    245 

Stream  line  tank    250 

Structural    279 

Students,  wireless   141 

Stupar   tractor    144 

Sturtevant  aeroplane    244,   291,  292 

Sulphuric   acid    169 

Summer  flying  suit 191 

Supply  of  gasoline    249 

Supply  guage    251 

Supplv    tanks    258 

Sullivan,  J.  D 210,  211 

Supremacy  of  the  air 39 

Swashbaffle  plates 248 

Synchronized  spark  gap    146,   147,  148 

Table   of  ascensional   forces    162 

Tables  of  density    260 

Tactical  reconnaissance  machines 245 

Tactics  in  air  duels   53 


298 


INDEX 


Tail  cups   164 

T»nk«     247 

Tarnt 71,  74.  76,   122 

Tsube     130 

Taylor.  CapL  R    L 210.  215 

Taylor.  Rear  Admiral  David  W 214.  215 

Technical   training,    balloons    163 

Tehanak.  City  of    91 

Teleiibone  car   82 

Telephonic    communication    159 

Tenth  Int.  Geog.  Congress 201.  203 

Temperature     260.  263 

Tennessee     211 

Tension     .  .    255,   256 

Teat  cut  out   270 

Testing  aeroplanes    259 

Ttating  cordage  and  fabric  for  balloons  .  . .    164 

Testing  Squadron    259.  261.  264 

Testa   for  aviators'    certificates    1S6 

Testa,  wind  channels   275 

Texms    211 

Texas  City.  Mex 205 

Thaw.   Lieut.  William   211.  241 

Thermometers    165 

Thermos    flask    261 

Thomas-Morse    291-292 

Thrust     256 

TUlottson.  Brig.  Oen.  Lee  S 212 

Timm  Aviation  Co 244 

Tiraudes     *^8 

Tiiard,  Capt.  H    P 259 

Toronto    216 

Toriiedoplane     12 

Torpedo  attacks    9 

Torque     247.   256 

Torsion     255 

Touring  Club  of  lUly   203 

Towers.   Lieut.  Commander  J.  H 202 

Training  aviators  for  IT.  .S.  Army 179 

Training   balloon  companies    164 

Training  fiilds    180,    187 

Training  Fifld.  American   186 

Training  machines    244 

Training  machines.  American 212 

Trajectory    32 

Transmission   of  messages 112 

Transmission,  wireless    141 

Tranfli>ortation.    balloons    81 

Trenches   70.  71.  75.  90.  105,  159 

Trenches.    British    130 

Trench  shelters    70 

Trentino  Army    6 

Trent  iuo   front    72 

Trial  flights 224 

Trieste  Raids    19 

TripUine  scout  "8-3"    244 

Triplane.  advantages  of 45 

Tri|>lane.  Caproni 278 

"Triiie  Hound"   13 

Tripoli    229 

Tropics,  uniforms   195 

Tubing  for  fuel  leads      ...    250 

Tulie    wagon    84 

Tuning  vibrator    142 

Turkish-German    iKwitions    125 

Tnrney,   George  W 202 

Turner.  K.  M 202 

Twin  motored   .J    N  Tractor    244 

Twin  motored  Handley  Page 276 

Two  engined  aeroplanes 239 

Two  place  machines    246 

Two  propeller  system 246 

Types  of  Aeronautic  Maiw 197 

Ubmt  biues 9.  21 

TTnifomi*  reguUtions   193 

Uniforms,  specifications   190 

Uniforms,  U.  S.  Aeronautic  Personnel  190.  193 

United  Eastern  Aero  Con 242.  299 

United  SUtea   7.   170.   173 

18S,    11)3.    195.  201,   212,   224.   245.  282 

aero  maiM    197 

•ertmautic  p<-rsonnel,  regulations  for  uni 

forma     190.  193 

aeronautics,  history  of 204 

armed  machine*    47 


United   States — Continued 

aviation  students    181 

dirigibles      . 157 

Government 223 

Government  wireless  seta 153 

Navy  Radio  Division   154 

training  of  aviators    179 

training  fields   186 

War   Department    222 

wireless  students 141 

United  States  Army  76,  204,  205,  208,  209,   245 

Aviation  School 210 

Balloon  Co 169 

Balloon    School    161,   163 

Balloon   School,   Ft.  Omaha 167 

biplanes,   V.  S 140 

gasoline  supply  system   242 

Reserve  Military  aviators  test    189 

service  insignia 190 

uniforms    195 

University  of  California    216 

Illinois     216 

Ohio    216 

Texas    216 

University  students  studying  aviation    ....  181 

Use  maps  and  compass  with  free  balloon   .  164 

Useful  load    245 

UsueUi,  C 203 

Valve  cord    163 

Valve  line    258 

Vanderbilt,  Col.  Cornelius   202 

Vanderhilt.    W.    K 202 

Variable-camber    wing    252 

inductance     148 

pitch   blade    254.  255 

pitch  propeller   253.  265 

pull     128 

radiators    252 

Varnishing  cotton  balloons    164 

Velocity    247 

Velocity  of  aeroplane 275 

Verdun    64.  128 

Vermont     212 

Verys  Light 75.  76.  128 

Verys  jtistol    73,  76 

V  formation    30 

Vibration      248 

Vibration   absorbing  material   252 

Vickers    gun     48.  72 

Vickers  Scout   286 

Vienna   International   Aeronautical   Federa- 
tion       201 

Vilas,   L.   A 202 

Villa's  raid    208 

Vincent.  J.  C 219 

Virginia     212 

Virginia  National  Guard   212 

Visual  signal  codes  for  balloons 164 

Vitriol   process    168 

Voisin 32.  47.  222,  228.  269.  290 

Voisin    Brothers    226 

Voisin-Peugeot  gun  plane   54 

Volunteer    forces     180 

Waldon,  Sidney  D 214,  215 

Walker.  J.  Bernard    217 

Walker.   .John   C 204 

Walvets    64 

Wanamaker.  Rodman   210 

War.   decision  of    3 

War   Department    179.  217  245 

Wardrop.  G.  Douglas   202 

Wards.  Lieut.  Forest   210 

Ward.  T.  P 211 

War  kites    99 

War  office 229 

War  with  Mexico 204 

Washington,   Cutting  A.,  radio  set 153 

Washington,   D.  C 179 

Washington  Signal  Corps  Flying  School    .  .  182 

Water  gas   for   hydrogen    176 

Watkins,  Lieut.  B.  O .  215 

Wave  length,   wireless    142 

Weight  saving 279 

Wellington,  quotation Ill 


Wendell,    Evert  Jansen    237 

Western  battle  front ]  107 

Western   front    's2,  98 

Western  theater  of  war   .'  13 

West  Virginia ' '  212 

Wheeler,  Lieut.  D.  R '.'..'.  215 

Wheeler,    Monroe    '  202 

Wheeler.   S.   S ,,]  202 

White.   Brig.-Gen.  George  H 211 

White  House    212.  217 

Whitney,    Harry   Payne    .'  202 

Wilhelmshavcn     7,  10 

WiUard.    Daniel    .'  214 

Willets.  Lieut.  W.  P 210.  211.  215 

William,  I.  R _'  230 

Williams  Aero   Co ,'.  244 

Willis.   Lieut.  R.  H ,  .  ,  208 

Willoughby.  Hugh  L 202 

Wilson    Aerial    Highway     200 

Winch  for  kite  balloons    159 

Wind  channel  experiments    275 

Winding    drum    igi 

Windlass     16I 

Windlass  wagon    gi 

Wing  construction    253 

Wing    section     259 

Winter  gloves  for  aviators 191 

Winter.    Lieut.  .John  C 204 

Wire  gauze  strainer   250 

Wireless   75,  76,  77,  121,  138 

aerials     ...    142 

aero  transmitter    150 

apparatus.    Breguet    148 

communication       139 

control  of  artillery  fire 142.  149 

Culver  .".et    154 

equipment     138 

observer      147 

helmet    138 

installation     148 

receiving  apparatus    152 

receiving  station 151 

receiving  trucks    144 

sets  for  U.  S.  Gov 153 

signaling     147 

speed  of  sending    141 

station,    German    ....  151 

transmission    141,  142 

transmission    sets    246 

trucks     145 

units     150 

Washington  set 153 

Wire  telephone   140 

Wise  Wood.   Henry  A 202,  217.  238 

WittemannLewis   Co 244.  291 

Wood,  Brig.  Gen.  J'red.  W 210 

Woodhouse,  Henry 201,  217,  234,  237 

Woods  bulls  eye    158 

Wright     222 

Wright  aeroplane    204,   207,  226  236 

Wright.  Captain  Frank  W 211 

Wright-Martin   Co 237,   291-292 

Wright.  Orville    

.  .  .  .202.    204,    205,    222,   224,    225.  226 

Wright,    Rev.    Milton    225 

Wright.  Wilbur    221.  225 

Young.  Brig.-Gen.  L.  W 211 

Young,  William  Wallace    202 

Zahm,   Francis  A 202 

Zeebrugge    7 

Zeppelins  20.  126,  134,  135.  137.  143.  157.   240 

bomb    37 

bomb  dropping  mechanism    22 

duly     127.   133 

raids    24,   125 

incendiary  Ijomb 34 

over  Berlin    156 

radio     154 

(See  Textbook  of  Naval  Aeronautics  and 
D'Orcy's  Airship  manual.) 

wireless    138 

wireless  stations    152 

wreck     110 

Zone  call  system    122 


^^ 


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